Butterflies Worth Knowing
by Clarence Moores Weed · English · Gutenberg #37009 · 505,128 chars · public domain (US)
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Title: Butterflies Worth Knowing
Author: Clarence Moores Weed
Release date: August 8, 2011 [eBook #37009]
Language: English
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[Illustration: _From a drawing by S. Shimotori_ _See page 120_
THE REGAL FRITILLARY, FEMALE]
_LITTLE NATURE LIBRARY_
=======================
BUTTERFLIES
WORTH KNOWING
BY CLARENCE M. WEED, D. Sc.
AUTHOR OF
_Seeing Nature First_, _Nature Biographies_, _Ten New
England Blossoms_, _The Flower Beautiful_, _etc._
[Illustration: "Fructus Quam Folia"]
_Illustrated by Forty-eight Plates
Thirty-two in Color_
PUBLISHED BY
DOUBLEDAY, PAGE & COMPANY
FOR
NELSON DOUBLEDAY, INC.
1922
_Copyright, 1917, by_
DOUBLEDAY, PAGE & COMPANY
_All rights reserved, including that of
translation into foreign languages,
including the Scandinavian_
PRINTED IN THE UNITED STATES
AT
THE COUNTRY LIFE PRESS, GARDEN CITY, N. Y.
PREFACE
In this little book an attempt has been made to discuss the more
abundant and widely distributed butterflies of eastern North America
from the point of view of their life histories and their relations to
their surroundings. In so doing I have of course availed myself of the
written records of a host of students of butterflies, without whose
labors no such volume would be possible. Among these two names stand
out preeminent--William H. Edwards and Samuel H. Scudder. Each was the
author of a sumptuous work on American butterflies to which all later
students must refer, both for information and for inspiration. Many
others, however, have made notable contributions to our literature of
these ethereal creatures. Every seeker after a knowledge of
butterflies will soon find himself indebted to the writings of such
investigators as the Comstocks, Denton, Dickerson, Dyar, Fernald,
Fiske, Fletcher, French, Hancock, Holland, Howard, Longstaff, Newcomb,
Riley, Skinner, Wright, and many others. I am glad to express my
obligations to all of these for the assistance their records have
given in the preparation of this book.
While a vast amount of knowledge of butterflies has already been
discovered there is still more to be learned concerning them, and
throughout these pages I have attempted to indicate the more important
opportunities awaiting investigation. The day of the field naturalist
has come again and the butterflies are well worthy of careful
observations by many interested students.
The illustrations in the book require a word of credit. The eleven
color plates of adult butterflies with wings spread have been made
direct from a set of the remarkable transfers which Mr. Sherman F.
Denton has been preparing for the last quarter-century, this
particular set having been prepared especially for this book.
Transfers of this sort were used as insets in Mr. Denton's work on the
"Moths and Butterflies of the United States," published in a limited
edition by J. B. Millet Company, Boston. The other plates not
reproduced from photographs are from drawings by Miss Mary E. Walker
or Mr. W. I. Beecroft. In case the photographs are not of my own
taking, credit is given beneath each. Two of my photographs have
already appeared in "Seeing Nature First" and are here used by
permission of its publishers, J. B. Lippincott Company.
C. M. W.
STATE NORMAL SCHOOL,
Lowell, Mass.
CONTENTS
PAGE
PREFACE v
LIST OF COLORED ILLUSTRATIONS xi
LIST OF OTHER ILLUSTRATIONS xiii
PART I
INTRODUCTION
BUTTERFLY TRANSFORMATIONS 5
BUTTERFLIES AND MOTHS 13
THE SCENTS OF BUTTERFLIES 15
BUTTERFLY MIGRATIONS 16
HIBERNATION OR WINTER LETHARGY 17
AESTIVATION OR SUMMER LETHARGY 21
FEIGNING DEATH IN BUTTERFLIES 22
COLORATION OF BUTTERFLIES 24
SELECTIVE COLOR SENSE IN BUTTERFLIES 32
WARNING COLORATION AND MIMICRY 33
HELIOTROPISM IN BUTTERFLIES 35
PARASITIC ENEMIES OF BUTTERFLIES 40
REARING BUTTERFLIES FROM CATERPILLARS 43
PHOTOGRAPHING BUTTERFLIES 47
BUTTERFLY COLLECTIONS 49
PART II
THE TRUE BUTTERFLIES--SUPERFAMILY _Papilionoidea_ 55
PARNASSIANS (_Parnassiinae_) 56
SWALLOWTAILS (_Papilionidae_) 57
Black Swallowtail; Giant Swallowtail; Blue Swallowtail;
Green-clouded Swallowtail; Tiger Swallowtail; Palamedes
Swallowtail; Short-tailed Papilio; Zebra Swallowtail;
Synopsis of the Swallowtails
WHITES, ORANGE-TIPS, AND YELLOWS (_Pieridae_) 82
The Tribe of the Whites: White or Imported Cabbage Butterfly;
Gray-veined White; Checkered White; Great Southern White;
Synopsis of the Whites 83
The Tribe of the Orange-tips: Falcate Orange-tip;
Olympian Orange-tip; Synopsis of the Orange-tips 92
The Tribe of the Yellows: Brimstone or Cloudless
Sulphur; Dog's-head; Clouded Sulphur; Orange
Sulphur; Pink-edged Sulphur; Black-bordered Yellow;
Little Sulphur; Dainty Sulphur; Synopsis
of the Yellows 97
NYMPHS (_Nymphalidae_) 111
The Tribe of the Fritillaries: Gulf Fritillary;
Variegated Fritillary; Diana Fritillary; Regal Fritillary;
Great Spangled Fritillary; Silver-spot Fritillary;
Mountain Silver-spot; White Mountain Fritillary;
Meadow Fritillary; Silver-bordered Fritillary;
Synopsis of the Fritillaries 115
The Tribe of the Crescent-spots: Baltimore Checker-spot;
Harris's Checker-spot; Silver Crescent; Pearl Crescent;
Synopsis of the Crescent-spots 135
The Tribe of the Angle-wings: Violet-tip; Hop-merchant
or Comma; Gray Comma; Green Comma; Red Admiral or Nettle
Butterfly; Painted Beauty; Painted Lady or Cosmopolite;
Mourning-cloak; American tortoise-shell; White J Butterfly
or Compton Tortoise; Buckeye; Synopsis of the Angle-wings
(I. Polygonias--II. Vanessids) 150
The Tribe of the Sovereigns: Viceroy; Banded Purple;
Red-spotted Purple; Vicereine; Synopsis of the Sovereigns 192
The Tribe of the Emperors: Goatweed Emperor; Gray Emperor;
Tawny Emperor; Synopsis of the Emperors 207
MEADOWS-BROWNS OR SATYRS (_Agapetidae_) 214
Common Wood Nymph or Grayling; Southern Wood Nymph;
Pearly Eye; Eyed Brown; White Mountain Butterfly; Arctic
Satyr; Little Wood Satyr; Other Meadow-browns; Synopsis of
Meadow-browns
HELICONIANS (_Heliconidae_) 229
Zebra Butterfly
MILKWEED BUTTERFLIES (_Lymnadidae_) 232
Monarch; Queen
SNOUT BUTTERFLIES OR LONG-BEAKS (_Libytheidae_) 236
Snout Butterfly
METAL-MARKS (_Riodinidae_) 239
Small Metal-mark; Large Metal-mark
GOSSAMER-WINGS (_Lycaenidae_) 240
The Tribe of the Hair-streaks: Great Purple Hair-streak;
Gray Hair-streak; Banded Hair-streak; Striped Hair-streak;
Acadian Hair-streak; Olive Hair-streak; Synopsis of the
Hair-streaks 242
The Tribe of the Coppers: Wanderer; American Copper;
Synopsis of the Coppers 252
The Tribe of the Blues: Spring Azure; Scudder's Blue;
Tailed Blue; Silvery Blue: Synopsis of the Blues 258
PART III
THE SKIPPER BUTTERFLIES--SUPERFAMILY _Hesperioidea_ 266
GIANT SKIPPERS (_Megathymidae_) 267
Yucca-borer Skipper
COMMON SKIPPERS (_Hesperiidae_) 268
The Tribe of the Larger Skippers: Silver-spotted Skipper;
Long-tailed Skipper; Juvenal's Dusky-wing; Sleepy
Dusky-wing; Persius's Dusky-wing; Sooty Wing 269
The Tribe of the Smaller Skippers: Tawny-edged Skipper;
Roadside Skipper; Least Skipper 278
LIST OF COLORED ILLUSTRATIONS
PAGE
VICEROY BUTTERFLIES VISITING STRAWBERRIES (_On Cover_)
THE REGAL FRITILLARY _Frontispiece_
THE CAROLINA LOCUST 33
THE BLACK SWALLOWTAIL 48
THE CYNTHIA MOTH 49
GIANT SWALLOWTAILS 64
THE BLUE SWALLOWTAIL 65
TWO OF THE SWALLOWTAILS: PALAMEDES AND GIANT 66
THE GREEN-CLOUDED SWALLOWTAIL 67
CATERPILLARS OF THE GREEN-CLOUDED SWALLOWTAIL 80
THE TIGER SWALLOWTAIL 96
IMPORTED CABBAGE BUTTERFLY 97
CLOUDED SULPHUR BUTTERFLY 112
THE ZEBRA SWALLOWTAIL: SUMMER FORM 112-113
THE ZEBRA SWALLOWTAIL VISITING PAPAW BLOSSOMS 112-113
SOME OF THE TRIBE OF YELLOWS 113
SILVER-SPOT FRITILLARY AND GULF FRITILLARY 128
GULF FRITILLARY, SILVER-BORDERED FRITILLARY,
AND BALTIMORE CHECKER-SPOT 129
THE HOP MERCHANT 144
THREE ANGLE-WINGS (AMERICAN TORTOISE-SHELL,
RED ADMIRAL, VIOLET-TIP): UPPER SURFACE 160-161
THREE ANGLE-WINGS (AMERICAN TORTOISE-SHELL,
RED ADMIRAL, VIOLET-TIP): LOWER SURFACE 160-161
THE PAINTED BEAUTY 161
THREE MORE ANGLE-WINGS: BUCKEYE, PAINTED BEAUTY, COSMOPOLITE 176
THE MOURNING-CLOAK 177
SOME COMMON SKIPPERS 192
THE STAGES OF THE VICEROY 193
BANDED PURPLE, RED-SPOTTED PURPLE, AND BLUE-EYED GRAYLING 208
THREE EMPEROR BUTTERFLIES 209
THE ZEBRA BUTTERFLY 224
MONARCH BUTTERFLY, CRYSALIS AND CATERPILLAR 241
SPRING AZURE, FALCATE ORANGE-TIP, BRONZE COPPER,
AND GREAT PURPLE HAIR-STREAK 256
SILVER-SPOTTED SKIPPER 273
LIST OF OTHER PLATES
PAGE
SWALLOWTAIL BUTTERFLY JUST OUT OF CHRYSALIS 16
TIGER SWALLOWTAIL; HAMMOCK CATERPILLAR 17
BUTTERFLY FEIGNING DEATH; BUTTERFLY IN HIBERNATING POSITION 32
MONARCH BUTTERFLY: CHANGE FROM CATERPILLAR TO CHRYSALIS 32-33
MONARCH BUTTERFLY: CHANGE FROM CHRYSALIS TO ADULT 32-33
MIGRATION OF MONARCH BUTTERFLIES 48-49
THE IMPROVED OPEN VIVARIUM 48-49
BLACK SWALLOWTAIL VISITING THISTLE 64-65
IMPORTED CABBAGE BUTTERFLY, MAGNIFIED 64-65
IMPORTED CABBAGE BUTTERFLY; BLUE-EYED GRAYLING 81
FOUR-FOOTED BUTTERFLIES: VICEROY AND MOURNING-CLOAK 145
MONARCH BUTTERFLY RESTING; FLASHLIGHT PHOTOGRAPH
OF MONARCHS IN MIGRATION 160
PHOTOGRAPHS OF A PET MONARCH BUTTERFLY 225
THE SNOUT BUTTERFLY; THE GIANT SWALLOWTAIL 240
STAGES OF THE GRAY HAIR-STREAK 257
THE SILVER-SPOTTED SKIPPER 272
BUTTERFLIES WORTH KNOWING
BUTTERFLIES
PART I
INTRODUCTION
In popular esteem the butterflies among the insects are what the birds
are among the higher animals--the most attractive and beautiful
members of the great group to which they belong. They are primarily
day fliers and are remarkable for the delicacy and beauty of their
membranous wings, covered with myriads of tiny scales that overlap one
another like the shingles on a house and show an infinite variety of
hue through the coloring of the scales and their arrangement upon the
translucent membrane running between the wing veins. It is this
characteristic structure of the wings that gives to the great order of
butterflies and moths its name Lepidoptera, meaning scale-winged.
In the general structure of the body, the butterflies resemble other
insects. There are three chief divisions: head, thorax, and abdomen.
The head bears the principal sense organs; the thorax, the organs of
locomotion; and the abdomen, the organs of reproduction.
By examining a butterfly's head through a lens it is easy to see the
principal appendages which it bears. Projecting forward from the
middle of the top is a pair of long feelers or antennae. Each of these
consists of short joints which in general may be divided into three
groups: first, a few large joints at the base connecting the feeler
with the head; second, many rather small joints which make up the
principal length; third, several larger joints which make up the outer
part or "club" of the antennae. In the case of the Skippers, there are
in addition a number of small joints coming to a sharp point at the
end of the club. Just below the insertion of the antennae on each side
of the head are the large compound eyes, which are almost
hemispherical. With a powerful glass, one can see the honeycomb-like
facets, of which there are thousands, making up each eye. Just below
the eyes there are two hairy projections, called the palpi, between
which is the coiled tongue or sucking tube. (_See plate, page 64-65._)
[Illustration: Butterfly Antennae, magnified. (From Holland)]
Anatomically the thorax is divided into three parts--the prothorax,
the mesathorax, and the metathorax; but the lines of division between
these parts are not easily seen without denuding the skin of its hairy
covering. The prothorax bears the first pair of legs. The mesathorax
bears the front pair of wings and the second pair of legs. The
metathorax bears the hind pair of wings and the third pair of legs. In
many butterflies, the first pair of legs are so reduced in size that
they are not used in walking.
The abdomen is composed of eight or nine distinct rings or segments,
most of which have two spiracles or breathing pores, one on each side.
It also bears upon the end of the body the ovipositor of the female
or the clasping organs of the male.
BUTTERFLY TRANSFORMATIONS
The butterflies furnish the best known examples of insect
transformations. The change from the egg to the caterpillar or larva,
from the caterpillar to the pupa or chrysalis, and from the chrysalis
to the butterfly or imago is doubtless the most generally known fact
concerning the life histories of insects. It is a typical example of
what are called complete transformations as distinguished from the
manner of growth of grasshoppers, crickets, and many other insects in
which the young that hatches from the egg bears a general resemblance
to the adult and in which there is no quiet chrysalis stage when the
little creature is unable to eat or to move about.
[Illustration: Egg of Baltimore Butterfly, much magnified.
(From Holland)]
_The Growth of the Caterpillars_
Caterpillars are like snakes in at least one respect: in order to
provide for their increase in size they shed their skins. When a
caterpillar hatches from the egg it is a tiny creature with a soft
skin over most of its body but with rather a firm covering for its
head. While we might fancy that there could be a considerable increase
in size provided for by the stretching of the soft skin it is easy to
see that the hard covering of the head will not admit of this. So the
story of the growth of a caterpillar may be told in this way:
A butterfly lays an egg upon a leaf. Some days later the egg hatches
into a larva, which is the technical name for the second stage of an
insect's life. In the case of the butterfly we call this larva a
caterpillar. The little caterpillar is likely to take its first meal
by eating the empty egg shell. This is a curious habit, and a really
satisfactory explanation of it seems not to have been made. Its next
meal is likely to be taken from the green tissues of the leaf,
commonly the green outer surface only being eaten at this time. The
future meals are also taken from the leaf, more and more being eaten
as the larva gets older.
After a few days of this feeding upon the leaf tissues the little
caterpillar becomes so crowded within the skin with which it was born
that it is necessary to have a larger one. So a new skin begins to
form beneath the first one. Consequently the latter splits open in a
straight line part way down the middle of the back just behind the
head. Then the new head covering is withdrawn from the old one and the
caterpillar wriggles its way out of the split skin and finds itself
clothed in a new one. At first all of the tissues of the new skin are
soft and pliable and they easily take on a larger size as the body of
the caterpillar expands. A little later these tissues become hardened
and no further expansion is possible.
This process of skin-shedding is called moulting. The cast skin is
often called the exuviae. The period of the caterpillar's life between
the hatching from the egg and this moult is often called a stage or
instar--that is, the caterpillar up to the time of this moult is
living in the first caterpillar stage or instar.
During the actual moulting the caterpillar is quite active in freeing
itself from the exuviae. But as soon as it is free it is likely to
rest quietly for some hours while the tissues of the new skin are
hardening. Then it begins feeding upon the leaf again and continues
taking its meals at more or less regular intervals for several days.
By that time it will again have reached its limit of growth within
this second skin and the process of moulting must be repeated. It
takes place in the same way as before and the caterpillar enters upon
the third instar of its larval life.
This process of feeding and moulting is continued for several weeks,
the number of moults being usually four. During the later stages the
increase in size is more marked each time the skin is shed, until the
caterpillar finally reaches its full growth as a larva and is ready
for the wonderful change to the quiet chrysalis in which all its
caterpillar organs are to be transformed into the very different
organs of the butterfly.
In the case of butterfly larvae one of the most interesting features
of the growth of the caterpillar is that of the remarkable changes in
colors and patterns of marking which the caterpillar undergoes. One
who had not followed these changes would often be at a loss to
recognize caterpillars of slightly differing sizes as belonging to the
same species. These changes commonly show a remarkable adaptation to
the conditions of life, and generally tend to the concealment of the
caterpillar upon its food plant. The stages of growth of the
green-clouded swallowtail caterpillar are illustrated on plate
opposite page 80.
Before each moult the caterpillar is likely to spin a silken web upon
the leaf surface. It then entangles its claws in the web to hold
itself in place while the skin is cast. (_See plate, page 17._)
_The Change to the Chrysalis_
(_See plate, pages 32-33._)
A week or ten days after the last moult of its caterpillar growth the
larva commonly becomes full fed and ready to change to the chrysalis
state. The details of the way in which this is accomplished vary
greatly with different butterflies, as will be noted in the stories of
many species later in this book. In general, however, the caterpillar
provides a web of silk which it spins against some surface where the
chrysalis will be secure and in this web it entangles its hind legs.
Sometimes there is the additional protection of a loop of silk over
the front end of the body. After the legs have become entangled the
caterpillar hangs downward until the skin splits open along the median
line of the back and gradually shrinks upward until it is almost free,
showing as it comes off a curious creature which has some of the
characteristic features of a chrysalis. It is seldom at this stage of
the same shape as the chrysalis. When the caterpillar's skin is nearly
off this chrysalis-like object usually wriggles its body quickly in a
manner to entangle a curious set of hooks attached to the upper end in
the web of silken thread. This hook-like projection is called the
cremaster, and it serves a very important purpose in holding the
chrysalis in position.
[Illustration: Swallowtail Chrysalis, showing (_b_) the loop of
silk over thorax. (After Riley)]
As soon as the cremaster is entangled in the web the cast skin usually
falls off and for a very short period the creature hanging seems to be
neither caterpillar nor chrysalis. It is in fact in a transition stage
between the two, and it very soon shortens up and takes on the
definite form of the chrysalis, the outer tissues hardening into the
characteristic chrysalis skin.
From the fact that this chrysalis skin shows many of the
characteristic features of the future butterfly it is evident that the
change from the caterpillar to the butterfly really began during the
life of the larva. The nature of the process by which this change
takes place has long been a puzzle to scientists. For the making of a
butterfly is one of the most wonderful phenomena in the outer world,
and it has challenged the attention of many acute observers. Some two
centuries ago the great Dutch naturalist, Swammerdam, studied very
carefully the development of many insects, especially the butterfly.
He found that if he placed in boiling water a caterpillar that was
ready to pupate or become a chrysalis, the outer skin could easily be
removed, revealing beneath the immature butterfly with well-developed
legs and antennae. From these observations he was led to believe that
the process of growth was simply a process of unfolding; that is, as
Professor Packard has expressed it, "That the form of the larva, pupa,
and imago preexisted in the egg and even in the ovary; and that the
insects in these stages were distinct animals, contained one inside
the other, like a nest of boxes or a series of envelopes one within
the other." This was called the incasement theory and it was held to
be correct by naturalists for nearly a century. It was discredited,
however, about a hundred years ago, but not until another fifty years
had passed was it definitely replaced by another and much more
convincing theory propounded by Weismann.
According to Weismann's theory, which is now well-established, the
process of development internally is a much more continuous one than
the external changes would indicate. So far as the latter are
concerned we simply say that a caterpillar changes to a chrysalis and
a chrysalis to a butterfly, the transition in each case requiring but
a very short time. Internally, however, it has been going on almost
continuously from the early life of the caterpillar. The various
organs of the butterfly arise from certain germinal disks or
"imaginal" buds, the word "imaginal" in this case being an adjective
form of imago, so that the imaginal buds are really simply buds for
the starting of growth of the various organs of the imago or adult. As
the caterpillars approach the chrysalis period these imaginal buds
rapidly develop into the various organs of the butterfly. This process
is helped along by the breaking down of many of the tissues of the
larva, this broken-down tissue being then utilized for the production
of the new organs. About the time the chrysalis is formed this
breaking-down process becomes very general, so that the newly formed
chrysalis seems largely a mass of creamy material which is soon used
to build up the various parts of the butterfly through the growth of
the imaginal buds.
_The Change to the Butterfly_
(_See plate, pages 32-33._)
There is probably no phenomenon in the world of living creatures which
has attracted more attention than the change of the chrysalis into the
butterfly. It is not strange that this is so. We see upon a tree or
shrub or wall an inert, apparently lifeless object, having no
definite form with which we can compare it with other things, having
neither eyes nor ears nor wings nor legs--an object apparently of as
little interest as a lifeless piece of rock. A few minutes later we
behold it again and note with astonishment that this apparently
inanimate being has been suddenly transformed into the most ethereal
of the creatures of earth, with an exquisite beauty that cannot fail
to attract admiration, with wings of most delicate structure for
flying through the air, with eyes of a thousand facets, with organs of
smell that baffle the ingenuity of man to explain, with vibrant
antennae, and a slender tongue adapted to feeding upon the nectar of
flowers--the most ambrosial of natural food. So it is not strange that
this emergence of a butterfly has long been the theme both of poets
and theologians and that it attracts the admiring attention of
childhood, youth, and age.
Fortunately, this change from chrysalis to butterfly may readily be
observed by any one who will take a little trouble to rear the
caterpillars or to watch chrysalids found outdoors. The precise method
of eclosion, as we call this new kind of "hatching," varies somewhat
with different species but in general the process is similar in all.
Those chrysalids which have a light colored outer skin are especially
desirable if we would watch this process. One can see through the
semi-transparent membrane the developing butterfly within, until
finally, just before it is ready to break out, the markings of the
wings and body show distinctly. If at this time the chrysalis is
placed in the sunshine it is likely to come out at once, so that you
can observe it readily. It usually breaks apart over the head and the
newly released legs quickly grasp hold of the empty skin as well as of
the support to which it is attached. It then hangs downward with a
very large abdomen and with the wings more or less crumpled up, but
decidedly larger than when they were confined within the chrysalis.
The wings, however, soon begin to lengthen as they are stretched out,
probably through the filling of the space by the body juices.
Commonly, the hind pair of wings become full size before the front
ones. In a short time the wings attain their full size, the abdomen
becomes smaller, through the discharge of a liquid called meconium,
and the butterfly is likely to walk a few steps to a better position
where it will rest quietly for an hour or two while body and wing
tissues harden. After this it is likely to fly away to lead the free
life of a butterfly. (_See plate, page 16._)
These changes from larva to chrysalis and from chrysalis to adult in
the case of the Monarch Butterfly are illustrated on the plates
opposite pages 32-33. A little study of these photographs from life
will help greatly to an understanding of the process.
Some very interesting observations have been made by Mr. J. Alston
Moffat upon the method of the expansion of the wings. In summarizing
his investigations he writes:
"When a wing is fully expanded, and for an hour or two after, the
membranes can be easily separated. Entrance for a pin-point between
them is to be found at the base of the wing where the subcostal and
median nervures come close together. The membranes are united at the
costal and inner edges, which have to be cut to get them apart; but
they are free at the outer angle. At that time the nervures are in two
parts, half in one membrane and half in the other, and open in the
centre. The fluid which has been stored up in the pupa enters the
winglet at the opening referred to, expanding the membranes as it
passes along between them, and the nervures at the same time, and when
it has extended to every portion of the wing, then it is fully
expanded. The expanding fluid is of a gummy consistency, and as it
dries, cements the membranes together, also the edges of the
half-nervures, and produces the hollow tubes with which we are so
familiar."
BUTTERFLIES AND MOTHS
The butterflies and moths both belong to the great order of
scale-winged insects--the Lepidoptera. They are distinguished,
however, by certain general characteristics, which hold true for the
most part in both groups. The butterflies fly by day; the moths fly by
night. All of the higher butterflies go into the chrysalis state
without making a silken cocoon, while most of the higher moths make
such a cocoon. The bodies of the butterflies are usually slender,
while those of the larger moths are stout. The antennae of the
butterflies are generally slender and commonly enlarged at the tip
into a miniature club. The antennae of the larger moths are commonly
feathery or are long and slender, tapering gradually toward the tip.
[Illustration: Butterfly wing scales, magnified.
(From Holland)]
The characteristic features that distinguish a moth from a butterfly
are well illustrated in the plate opposite page 49, which shows one of
the largest and most beautiful moths in the world. It is the Cynthia
moth. As may be seen, the newly emerged moth is resting upon the
silken cocoon in which it spent its period as a pupa or chrysalis.
This cocoon was attached by the caterpillar to the twig from which it
hangs at the time it spun the cocoon. The feathered antennae, the
hairy legs, the thick thorax, and large abdomen--all show very clearly
in this side view of the moth. As will be seen, the wings are large
and very suggestive of those of a butterfly and have the
characteristic eye-spots toward the tip and the crescent marks in the
middle, which are so often found on the wings of the larger moths.
Some of these large moths on cloudy days occasionally fly during
daylight and, by the uninitiated, they are often mistaken for large
butterflies. One who will notice their structure, however, will
readily see the characteristic features of the moth.
In the caterpillar stage, there are no hard and fast differences
between the larvae of butterflies and those of the higher moths. In
each case, the insect consists of a worm-like body, having a small
head provided with biting jaws and simple eyes or ocelli. Back of the
head are the three rings of the thorax, each of which bears a pair of
jointed legs. Back of these three rings there are a considerable
number of other body rings making up the abdomen, on the middle of
which there are commonly four or five pairs of fleshy prolegs, not
jointed but furnished at the tip with fine claws. At the hind end of
the body there is another pair of prolegs similar in structure.
THE SCENTS OF BUTTERFLIES
Many students of American butterflies have occasionally mentioned the
fact that certain species seem to give off a distinct scent which has
frequently been spoken of as a pleasing fragrance, suggesting
sandalwood or some other aromatic odor. The general subject as
exemplified by butterflies of other lands has been studied for many
years by Fritz Mueller; and certain English entomologists have paid
considerable attention to it. A translation of the Mueller publications
and an excellent summary of our present knowledge of the subject is
published in Dr. Longstaff's book on butterfly hunting.
The odors given off by butterflies are divided into two principal
kinds, namely: first, those which are repulsive to the senses of man,
and evidently for the purpose of protecting the butterflies from birds
and other vertebrate enemies--these are found in both sexes; second,
those which are evidently for the purpose of sexual attraction and
confined to the male butterflies--these scents are usually attractive
to the senses of man.
[Illustration: Androconia from wings of male butterflies]
The aromatic scents of the second group are generally produced by
means of certain scales or hairs of many curious forms, which are
scattered over the surface of the wings or are placed within certain
special pockets, generally near the borders of the wings. These scales
or hairs are called androconia. Some of them much magnified are
represented in the picture above.
Our knowledge of the scents given off by American butterflies is very
fragmentary, and it is highly desirable that many more observations
should be made upon the subject. If collectors generally would make
careful notes, both in the field and upon the freshly killed
butterflies at home, we ought soon to be able greatly to extend our
knowledge. By holding the butterfly with a pair of forceps, one can
often determine whether the fragrance is emitted. It is often helpful
also to brush the hairs or tufts where the androconia are attached,
using a small, dry camel's hair brush for the purpose.
BUTTERFLY MIGRATIONS
Migration seems to be a general instinct in the animal world,
developed when a species becomes enormously abundant. At such times
this instinct apparently overcomes all others and the creatures move
on regardless of obstacles and conditions that may mean certain death
to the vast majority. Such migrations among mammals have often been
recorded, one of the most notable examples being that of the little
lemmings which migrate at periodical intervals in a way which has
often been described. Among the insects such migrations have been
frequently noticed, and the phenomenon has apparently been observed
oftener among the butterflies than in any other group. Entomological
literature during the last hundred years contains a great many records
of enormous flights of butterflies over long distances, extending even
from Africa into Europe or from one part of America to another far
remote. As such migration is likely to happen whenever a species
becomes extremely abundant it probably is Nature's way of providing
for an extended food supply for the succeeding generations. That it
results in the death of the great majority of the migrants is
doubtless true, but it must lead to vast experiments in extending the
geographic area inhabited by these species. Numerous examples of such
migrating swarms will be found in the pages of this little book. (_See
plates, pages 17,48-49, 160._)
[Illustration: _Photographed from life by A. H. Verrill_
_See page 12_
SWALLOWTAIL BUTTERFLY JUST OUT OF ITS CHRYSALIS.
THE CHRYSALIS SKIN BELOW]
[Illustration: _See page 72_
TIGER SWALLOWTAIL]
[Illustration: _Photographed from life_ _See page 7_
THE HAMMOCK CATERPILLAR ON ITS HAMMOCK]
The migrations thus considered are only exceptional occurrences. There
is, however, a regularly recurring annual migration on the part of
some butterflies which is also a phenomenon of extraordinary interest.
The most notable example is that of the Monarch which apparently
follows the birds southward every autumn and comes northward again in
spring. There is much evidence to indicate that in some slight degree
other butterflies have a similar habit, although the present
observations are inadequate to determine to what extent this habit has
become fixed in most of these species.
HIBERNATION OR WINTER LETHARGY
The ways in which butterflies spend the winter are always of peculiar
interest to the naturalist. Here are creatures with four distinct
stages of existence, each of which has the possibility of carrying the
species through the season of cold. It is necessary to learn for each
insect which stage has been chosen for the purpose, and if possible to
find the reasons for the choice.
As a rule the related members of a group are likely to hibernate in a
similar stage. Thus most of the Swallowtails pass the winter as
chrysalids while practically all the Angle-wings pass the winter as
adults. This rule, however, has many exceptions, for one will often
find closely related species which differ in the stage of hibernation.
As one would expect, the conditions of hibernation vary greatly with
the latitude. In the severe climate of the far north the conditions
are likely to be more uniform than in the South where the milder
climate permits greater variation to the insect. In some cases where a
butterfly hibernates in only one stage in Canada it may pass the
winter in two or more stages in Alabama or Florida.
In many other orders of insects the egg is a favorite stage for
hibernation. Even in the closely related moths it is often chosen by
many species, but comparatively few butterflies pass the winter in the
egg stage. The little Bronze Copper may serve as one example of this
limited group.
The conditions as to hibernation by the larvae of butterflies are very
different from those of the egg. It has been estimated that probably
half of all our species pass the winter in some stage of caterpillar
growth. This varies all the way from the newly hatched caterpillar
which hibernates without tasting food to the fully grown caterpillar
which hibernates full fed and changes to a chrysalis in spring without
eating anything at that time. A large proportion, however, feed both
in fall and spring, going through the winter when approximately half
grown.
The Graylings and the Fritillaries are typical examples of butterflies
which hibernate as newly hatched larvae. The eggs are laid in autumn
upon or near the food plants and the caterpillars gnaw their way out
of the shells and seek seclusion at once, finding such shelter as they
may in the materials on the soil surface. In spring they begin to feed
as soon as the weather permits and complete their growth from then
on.
The half-grown caterpillars may hibernate either as free creatures
under boards, stones, or in the turfy grass, or they may be protected
by special shelters which they have provided for themselves in their
earlier life. In the case of the latter each may have a shelter of its
own or there may be a common shelter for a colony of caterpillars.
Among the examples of those hibernating in miscellaneous situations
without special protection the caterpillars of the Tawny Emperor, the
Gray Emperor, the Pearl Crescent, and some of the Graylings are
examples. Among those which hibernate in individual shelters the
Sovereigns, among which our common Viceroy is most familiar, are good
examples. Among those which hibernate in a tent woven by the whole
colony for the whole colony the Baltimore or Phaeton butterfly is
perhaps the best example.
The caterpillars that hibernate when full grown may be grouped in a
way somewhat similar to those which are half grown. Many species
simply find such shelter as they may at or near the soil surface. The
Clouded Sulphur is a good example of these. Others pass the winter in
individual shelters made from a leaf or blade. Several of the larger
Skippers are good examples of this condition. So far as I know none of
our species pass the winter in colonial shelters when full grown.
It would be natural to suppose that the great majority of butterflies
would be likely to hibernate in the chrysalis state. Here is a quiet
stage in which the insect is unable to move about or to take any food,
in which it seems entirely dormant and as a rule is fairly well hidden
from the view of enemies. We find, however, that only a rather small
proportion of our butterflies has chosen this stage for survival
through the winter. The most conspicuous examples are the
Swallowtails, nearly all of which hibernate in the chrysalis stage.
Other examples are the various Whites, the Orange-tips, and isolated
species like the Wanderer, and the Spring Azure and the American
Copper. Practically all the butterflies that pass the winter as
chrysalids have a silken loop running around near the middle of the
body which helps to hold them securely through the long winter months.
Apparently none of those chrysalids which hang straight downward are
able to survive the winter.
An adult butterfly seems a fragile creature to endure the long cold
months of arctic regions. Yet many of our most beautiful species
habitually hibernate as adults, finding shelter in such situations as
hollow trees, the crevices in rocks, the openings beneath loose bark
or even the outer bark on the under side of a large branch. It is
significant that most of the adult-wintering Angle-wings are northern
rather than southern species, some of them being found in arctic
regions practically around the world. One of the few southern forms
that hibernates as an adult is the Goatweed Emperor.
These examples are all cases of true hibernation in a lethargic
condition. There are certain butterflies, however, which pass the
winter as adults that remain active during this period. Obviously this
is impossible in latitudes where the winter is severe, and it involves
migration to a warmer climate. The one notable illustration of this is
the Monarch butterfly which apparently flies southward to the Gulf
states at least and there remains until spring, when individuals come
north again. The southward migration may be begun in Canada when the
butterflies gather together in enormous flocks that remind one of the
gathering of the clans with the migrating birds. This is one of the
least understood of insect activities but it has been observed so
often and over so long a period of years that there seems to be no
questioning the general habit.
Like everything else in relation to living things there are numerous
variations in the prevailing modes of hibernation. In the case of many
species one can find combinations of two or more stages in which the
winter is passed. Probably if we could observe with sufficient care we
might be able to find somewhere examples of almost any conceivable
double combination--as egg with larva or chrysalis or adult--the
insect hibernating in two of these stages. Many examples are known in
which both chrysalis and adult of the same species pass the winter and
also of those in which young and well-grown larvae pass the winter. As
one would expect, the conditions as to such combinations are likely to
be more variable in southern than in northern regions.
Notwithstanding all the attention which has been paid to butterfly
life-histories there is still some uncertainty in regard to the
hibernation of many of our species. One of the most interesting series
of observations which a young naturalist could undertake would be to
learn positively how each species of butterfly in his locality passes
the winter.
AESTIVATION OR SUMMER LETHARGY
In some species of butterflies there is a special adaptation to
passing through the hottest part of the summer season in a state of
lethargy which is suggestive of the torpor of the hibernating period.
This phase of butterfly existence has not been extensively studied and
there are indications that it exists more generally than has been
commonly supposed. It has been noticed even in northern New England
that some of the Angle-wings seek shelter and become lethargic during
August. Apparently this is an adaptation to single broodedness,
helping to carry the species through the year without the exhaustion
incident to the continued activity of the butterfly.
In more southern regions, especially in the hot, dry climates where
vegetation withers in midsummer, it is well known that some
caterpillars become lethargic, remaining inactive until the fall rains
start vegetation into growth. The Orange-sulphur butterfly is a good
example of this.
This summer lethargy offers excellent opportunity for careful study.
Any observer who finds a butterfly hidden away in summer under boards,
the bark of a tree, or in a stone pile should look carefully to see
what species it is and how the butterfly behaves. Such observations
should be sent to the entomological journals in order that our
knowledge of the subject may be increased.
FEIGNING DEATH
The fact has long been noticed that various butterflies have the habit
at times of feigning death and dropping to the ground where they may
lie motionless for a considerable period. This habit is most easily
observed in some of the Angle-wings, especially those which hibernate
as adults. Those species have the under surfaces of their wings
colored in various bark-picturing patterns and apparently live
through the winter to some extent, resting beneath the bark of large
branches or upon the trunks of trees. Many of them also secrete
themselves in hollow trees or beneath loose bark or in board piles or
stone walls. It is probable, however, that during the long ages when
these insects were adapting themselves to their life conditions,
before man interfered with the natural order and furnished various
more or less artificial places for hibernation, these butterflies
rested more generally upon the under side of branches than they do
now.
Even in warm weather when one of these butterflies is suddenly
disturbed it is likely to fold its legs upon its body and drop to the
ground, allowing itself to be handled without showing any signs of
life. This habit is doubtless of value, especially during hibernation
or possibly during the summer lethargy or aestivation, the latter a
habit which may be more general among these butterflies than is now
supposed. As the insect lies motionless upon the ground it is very
likely to blend so thoroughly with its surroundings that it becomes
concealed, and any bird which had startled it from the branch above
would have difficulty in finding it.
Some very interesting observations have been made upon the
death-feigning instincts of various other insects, especially the
beetles. But no one so far as I know has yet made an extended study of
the subject in relation to our American butterflies. It is an
excellent field for investigation and offers unusual opportunities for
photographic records. One of the pictures opposite page 32 shows a
photograph which I took of a Mourning Cloak as it was thus playing
'possum. This species exhibits the instinct to a marked degree.
COLORATION
The caterpillars of butterflies and moths form a large part of the
food of insect-eating birds. These caterpillars are especially adapted
for such a purpose and in the economy of nature they play a very
important part in keeping alive the feathered tribes. During the long
ages through which both birds and insects have been developing side by
side, there have been many remarkable inter-relations established
which tend on the one hand to prevent the birds from exterminating the
insects and on the other to prevent the insects from causing the birds
to starve. The most important of these, so far as the caterpillars are
concerned, are the various devices by which these insects protect
themselves from attack, by hiding away where birds are not likely to
find them, by clothing their bodies with spiny hairs, by other methods
of rendering themselves distasteful, or by various phases of
concealing coloration. On the whole, the examples of the latter are
not so numerous or so easily found in the case of the larvae of
butterflies as in those of moths.
Perhaps the basal principle of concealing coloration is the law of
counter-shading, first partially announced by Prof. E. B. Poulton, and
later much more elaborately worked out by Mr. Abbott H. Thayer, and
discussed at length by Mr. Gerald H. Thayer in his remarkable volume,
"Concealing Coloration in the Animal Kingdom." The law of
counter-shading is tersely stated in these words: "Animals are painted
by nature darkest on those parts which tend to be most lighted by the
sky's light and _vice versa_." As this law works out on most animals
that live on or near the ground, the upper part of the body exposed
to the direct light from above is dark; and the under part, shut off
from the upper light and receiving only the small reflection from
below, is enough lighter to make the appearance of the creature in its
natural environment of a uniform tone from back to breast.
Nearly all caterpillars illustrate this law of counter-shading. If
they are in the habit of feeding or resting with their feet downward
the back will be darker and the under side lighter, but if they are in
the habit of feeding or resting in the opposite position these color
tones will be reversed. One can find examples of such conditions
almost any summer's day by a little searching of trees or shrubs.
This law of counter-shading, however, is really only the basis for the
coloration of caterpillars or other animals. It tends, chiefly, to
make the creature appear as a flat plane when seen from the side, and
may be said in a way to prepare the canvas upon which Nature paints
her more distinctive pictures. A great many examples of color markings
that tend to conceal the caterpillar amid its natural surroundings may
be found by any one who will study the subject and it offers one of
the most interesting fields for investigation. The chapter on
caterpillars in the above-mentioned book by Mr. Thayer should serve as
a starting point for any one taking up the subject.
Butterflies differ from caterpillars and from most other animals in
the fact that their coloring is chiefly shown upon the flat surfaces
of the wings. Consequently, there is less opportunity for the various
phases of counter-shading which is so commonly shown in the larger
caterpillars. The bodies of nearly all butterflies do exhibit this
phenomenon, but these bodies are relatively so small that
counter-shading plays but a little part in the general display.
Upon the outstretched membranes of the butterflies' wings Nature
through the long ages of development has painted a great variety of
pictures. Those which tend to protect the insect by concealment amid
its surroundings are most commonly spread on the under surface of the
wings. Especially is this true in the case of those species which pass
the winter as adults or which have the habit of resting upon the bark
of trees, the sides of rocks, or the surface of the ground. We here
find some of the most interesting examples of obliterative coloring
that occur in nature. Some butterflies have taken on the look of tree
bark, others the sombre appearance of weathered rocks, while still
others are painted with the images of flowerets and their stems.
_Dazzling and Eclipsing Colors_
Many of the butterflies, especially the Angle-wings, which are marked
on the under surface in various protective colors, are admirable
examples of that phase of animal coloring which is spoken of as
_dazzling coloration_. This is apparently one of the most important
protective devices to be found in Nature and the validity of it is now
generally conceded by naturalists. One phase of it, which may be
called eclipsing coloration, seems to have been first definitely
formulated by the late Lord Walsingham, a famous English entomologist
who enunciated it in an address as president of the Entomological
Society of London. The most significant paragraphs in that address
were these:
"My attention was lately drawn to a passage in Herbert Spencer's
'Essay on the Morals of Trade.' He writes: 'As when tasting different
foods or wines the palate is disabled by something strongly flavored
from appreciating the more delicate flavor of another thing afterward
taken, so with the other organs of sense a temporary disability
follows an excessive stimulation. This holds not only with the eyes in
judging of colors, but also with the fingers in judging of texture.'
"Here, I think, we have an explanation of the principle on which
protection is undoubtedly afforded to certain insects by the
possession of bright coloring on such parts of their wings or bodies
as can be instantly covered and concealed at will. It is an undoubted
fact, and one which must have been observed by nearly all collectors
of insects abroad, and perhaps also in our own country, that it is
more easy to follow with the eye the rapid movements of a more
conspicuous insect soberly and uniformly colored than those of an
insect capable of changing in an instant the appearance it presents.
The eye, having once fixed itself upon an object of a certain form and
color, conveys to the mind a corresponding impression, and, if that
impression is suddenly found to be unreliable, the instruction which
the mind conveys to the eye becomes also unreliable, and the rapidity
with which the impression and consequent instruction can be changed
cannot always compete successfully with the rapid transformation
effected by the insect in its effort to escape."
Lord Walsingham then goes on to suggest that this intermittent play of
bright colors probably has as confusing effect upon birds and other
predaceous vertebrates as upon man; and that on this hypothesis such
colors can be accounted for more satisfactorily than upon any other
yet suggested. Since then the significance of this theory has been
repeatedly pointed out by Professor Poulton, Mr. Abbott H. Thayer, and
various other authorities upon animal coloring. The terms _dazzling_
and _eclipsing_ have been applied to the phenomenon.
Shortly after Lord Walsingham propounded this theory I called
attention [A] to its fitness in explaining some of the most interesting
color phases shown by American insects, notably the moths and locusts
which have brilliantly colored under wings and protectively colored
upper wings.
[A] _Popular Science Monthly_, 1898, "A Game of Hide and Seek."
Reprinted in the _Insect World_, 1899.
The animals of the north show numberless color phases of interest. One
of the most curious of these is exhibited by several families of
insects in which the outer wings are protectively colored in dull hues
and the under wings brightly colored. For example, there are many
species of moths belonging to the genus Catocala found throughout the
United States. These are insects of good size, the larger ones
measuring three inches in expanse of wings, and the majority of them
being at least two thirds that size. Most of them live during the day
on the bark of trees, with their front wings folded together over the
back. The colors and markings of these wings, as well as of the rest
of the exposed portions of the body, are such as to assimilate closely
with the bark of the tree upon which the insect rests. In such a
situation it requires a sharp eye to detect the presence of the moth,
which, unless disturbed, flies only at night, remaining all day
exposed to the attacks of many enemies. Probably the most important of
these are the birds, especially species like the woodpeckers, which
are constantly exploring all portions of the trunks of trees.
The chief beauty of these Catocalas, as they are seen spread out in
the museum cabinet, lies in the fact that the hind wings, which, when
the moth is at rest in life, are concealed by the front ones, are
brightly colored in contrasting hues of black, red, and white in
various brilliant combinations. These colors, in connection with the
soft and blended tones of the front wings, make a very handsome
insect.
It is easy to see that when one of these Underwing Moths is driven to
flight by a woodpecker or other bark-searching bird it would show
during its rapid, irregular flight the bright colors of the under
wings which would be instantly hidden upon alighting and the very
different coloring of the upper wings blending with the bark would be
substituted. Consequently, the bird would be very likely to be baffled
in its pursuit.
_Coloration of Locusts_
On the rocky hills and sandy plains of New England there are several
species of grasshoppers or locusts that also illustrate these
principles. If you walk along a strip of sandy land in summer, you
start to flight certain locusts which soon alight, and when searched
for will be found closely to assimilate in color the sand upon which
they rest. On a neighboring granite-ribbed hill you will find few if
any of this species of locust, but instead there occur two or three
quite different species, which when at rest closely resemble the
lichen-covered rocks. This resemblance is very striking, and is found
in all stages of the insect's existence. If now you go to a lowland
meadow, still another color phase will be found to prevail--the green
grass is swarming with the so-called "long-horned" grasshoppers,
which are green throughout with linear bodies, and long, slender legs
and antennae.
Each of these three groups of insects is adapted to its particular
habitat. All are constantly persecuted by birds, and have been so
persecuted for unnumbered ages in the past. In every generation the
individuals have varied, some toward closer resemblance to
environment, others in an opposite direction. The more conspicuous
insects have been constantly taken, and the least conspicuous as
constantly left to reproduce. Were the three groups to change places
to-day, the green grasshoppers from the meadows going to sandy
surfaces, the sand-colored locusts going to rocky hills, and the
"mossbacks" from the hills to the lowland meadows, each would become
conspicuous, and the birds would have such a feast as is seldom spread
before them.
The species living on sand and rocks are often "flushed" by birds.
Those which flew but a few feet would be likely to be captured by the
pursuing bird; those which flew farther would stand a better chance of
escaping. Similarly, those which flew slowly and in a straight line
would be more likely to be caught than those which flew rapidly and
took a zigzag course. As a consequence of the selection thus brought
about through the elimination of those which flew slowly along the
straight and narrow way that led to death, you will find that most
locusts living in exposed situations when startled fly some distance
in a rapid, zigzag manner.
But still another element of safety has been introduced by some
species of these locusts through the adoption of the color tactics of
the Catocala moths. The under wings of the common Carolina locust--the
species most abundant along the highway--are black, bordered with
yellowish white. The base of the hind wings of a related species
living on the Western plains is bluish, while in the large
coral-winged locust of the Eastern states the hind wings are red,
bordered with black. In nearly all of the species of these locusts
frequenting open localities where they are liable to disturbance by
birds or other animals, the hind wings exhibit contrasting colors in
flight. Most of them also fly in a zigzag line, and alight in a most
erratic manner. Many times I have had difficulty in determining the
exact landfall of one of these peculiar creatures, and I believe Lord
Walsingham's suggestion is well exemplified in them. (_See page 33._)
The most famous example of a combination of this dazzling coloring of
the upper wing surface with a definite protective coloring of the
under wing surface is the Kallima butterfly which is illustrated in
almost every book dealing with animal coloration. The under wing
surface bears a striking resemblance to a leaf and the hind wings
project to form a tail which looks like the petiole of the leaf, and
there is also a mark running across the wings which mimics the midrib.
When the butterfly is flying the brilliant colors of the upper surface
are visible, but when it alights these are instantly replaced by the
sombre tone of the under surface, so that apparently the insect
completely disappears and in its place there is only a leaf attached
to a branch in a most natural position. In Dr. Longstaff's book there
is an illustration of another tropical butterfly, _Eronia cleodora_,
which resembles on its under surface a yellow disease-stricken leaf
but on its upper surface gives a brilliant combination of black and
white. This insect alights upon the leaves which it resembles and is
a striking example of both dazzling and mimicking coloration.
Many of our own butterflies, notably the Angle-wings, are excellent
examples of a similar combination. In flight they reveal conspicuous
colors which are instantly hidden upon alighting and then one only
sees the bark-like or dead leaf-like under surface as may be seen in
the plate opposite pages 160-161. The iridescence upon the upper wing
surface of many butterflies, whose under wing surface is colored in
concealing tones, is doubtless also of great use to the insect in a
similar way. There is a splendid opportunity here for some observer to
study this phase of butterfly activity and to get photographs of the
insects amid their natural surroundings.
In their book upon "Concealing Coloration" the Messrs. Thayer have
called attention to many interesting phases of dazzling coloration.
They show that bright marks like the eye-spots or ocelli, which form
so prominent a feature on the wing surfaces of many butterflies,
really helped to conceal the insect amid its natural surroundings, by
drawing the eye away from the outlines of wings and body so that the
latter tend to disappear. Their discussion of this subject opens up
another vast field for outdoor observations of absorbing interest, in
which there is great need for many active workers.
[Illustration: _See page 23_
BUTTERFLY FEIGNING DEATH, HANGING TO BARK BY ONE FOOT]
[Illustration: _See page 17_
BUTTERFLY IN HIBERNATING POSITION]
[Illustration: Caterpillar feeding upon leaf of milkweed
Caterpillar hung up for the change to the chrysalis
The transition stage
The Chrysalis
THE MONARCH BUTTERFLY: CHANGE FROM CATERPILLAR TO CHRYSALIS.
Photographs from life. (_See pages 8-10, 233_)]
[Illustration: Chrysalis showing butterfly ready to emerge
The empty chrysalis
Butterfly just out of chrysalis
Side view a little later
THE MONARCH BUTTERFLY: THE CHANGE FROM CHRYSALIS TO ADULT.
Photographs from life (_See pages 10-13, 235_)]
[Illustration: _See page 30_
THE CAROLINA LOCUST
Above, with wings expanded as in flight]
SELECTIVE COLOR SENSE
One who collects the Underwing moths soon discovers that the light
colored species which resemble the bark of birch trees are likely to
be found upon the trunks of those trees, and that the dark colored
kinds which resemble the bark of maple trees are likely to be found
upon the trunks of these. Obviously, were this not true the protective
coloring would avail but little and it is evident that these moths are
able to select a background which is of advantage in helping to
conceal them.
There is much evidence to show that in a similar way the butterflies
are able by means of a well-developed color sense to select the places
where they alight. One of the most notable examples is that of a South
American species, _Peridromia feronia_. This is a silvery gray
butterfly which alights head downward upon the bark of certain palm
trees that have silvery gray stems and remains there with its wings
fully expanded so that it utilizes the background in much the same way
that the Underwing moths do. "When disturbed they will return to the
same tree again and again."
One who will observe the habits of our Angle-wings and other
butterflies which have obliterative coloring of the under wing surface
can easily learn that these insects select rather carefully the places
where they alight. It will be found that as a rule each species
utilizes a background that blends with its own coloring. It is
probable that this habit is much more common in other groups of
butterflies than has been realized. Much evidence of this sort has
been collected regarding the butterflies of Europe and other
countries, as well as near our own borders in America.
WARNING COLORATION AND MIMICRY
The colors of a great many animals, including a considerable
percentage of American butterflies and their larvae, have been
commonly explained by the theory of _warning colors_. According to
this theory animals which were for any reason not edible by birds and
mammals have developed various striking combinations of color such as
black and yellow, red and black, or black and white, in order to
advertise to their foes their inedible qualities. This theory has been
very generally accepted by naturalists and will be found expounded at
length in many books published during the last quarter century.
The whole subject of the validity of warning coloration has recently
been brought up for reconsideration by the illuminating investigations
of Mr. Abbott H. Thayer and discussed at length in the book upon
"Concealing Coloration" already mentioned. In an appendix to this book
dated 1908 Mr. Thayer states that he no longer holds the belief that
"there must somewhere be warning colors." He has convincingly shown
that a large proportion of the animals which were supposed to be
examples of this theory are really illustrations of concealing
coloration. But there yet remain various facts which have been
conclusively proven that apparently require the theory of warning
colors to explain them. Here is another field in which there is a real
need for much careful investigation under conditions that are rigidly
scientific.
Along with the theory of warning coloration the theory of _mimicry_
has been propounded. According to this if a butterfly in a given
region shows warning coloration, having developed such coloration
because it is distasteful to birds and mammals, it may be mimicked by
another butterfly in the same region belonging to another group, the
latter butterfly being edible, but benefiting by its resemblance to
the distasteful species, because birds or mammals mistake it for the
latter and do not attempt to catch it. The most notable example of
such mimicry in North America is that of the Monarch butterfly, which
is supposed to be the distasteful species, and the Viceroy butterfly,
which is supposed to mimic it. Several other instances of mimicry are
found among our own butterflies, while in South America, Africa, and
Asia there are numberless examples.
HELIOTROPISM
It has long been known that the green surfaces of plants respond to
the stimulus of the sun's rays in a most remarkable manner. This
response has commonly been called _heliotropism_ and it has been
carefully studied by botanists all over the habitable world. More
recently, the fact has been observed that many animals respond in
certain definite ways to the stimulus of direct sunshine and the same
term has been applied in this case. Very little attention has been
given to the subject of heliotropism until within a few recent years.
But the observations which have been made by Parker, Longstaff, Dixey,
and others open up a most interesting field for further observation.
An admirable summary of our present knowledge of the subject has been
published by Dr. Longstaff in his book "Butterfly Hunting in Many
Lands."
One of the earliest observations upon this subject was that published
in my book "Nature Biographies" which appeared in June, 1901,
concerning the habit in the Mourning Cloak: "On a spring-like day
early in November (the 8th) I came across one of these butterflies
basking in the sunshine upon the ties of a railway track. It rested
with its wings wide open. On being disturbed, it would fly a short
distance and then alight, and I was interested to notice that after
alighting it would always turn about until the hind end of its body
pointed in the direction of the sun, so that the sun's rays struck its
wings and body nearly at right angles. I repeatedly observed this
habit of getting into the position in which the most benefit from the
sunshine was received, and it is of interest as showing the extreme
delicacy of perception toward the warmth of sunshine which these
creatures possess."
A little later, some very elaborate observations were made upon this
habit of the Mourning Cloak by Prof. G. H. Parker of Harvard
University. Professor Parker noticed that during the warm spells in
winter the butterflies came out of their hiding places and after
alighting, always placed themselves with their heads away from the
direction of the sun and their bodies lying nearly at right angles to
the sun's rays. By experiment, he found that they adjusted themselves
to this position as soon as they were fully exposed to direct
sunshine, even if at the time of alighting they were in a shadow. He
found that this movement was a reflex action through the eyes, for
when the eyes were blinded no such adjustment took place. He called it
_negative heliotropism_.
Dr. Longstaff uses the term _orientation_ for this adjustment of the
butterfly to the sun's rays and he finds it is a very general habit,
especially with the Angle-wings, for the butterfly thus to orient
itself after alighting, in such a way that the hind end of the body
points toward the sun. This occurs not only with those species which
keep their wings spread open when they alight but also with those in
which the wings are closed together and held in a vertical position on
alighting.
Various explanations of this phenomenon have been offered but
apparently none of them are yet generally accepted. Were the habit
confined to butterflies like the Mourning Cloak, it would seem easy to
prove that a main advantage was found in the benefit derived from the
heat rays of the sun. Were it confined to those species which always
fold their wings on alighting, it would seem easy to believe that it
was a device for reducing the shadow cast by the insect to its lowest
terms. It has also been suggested that the habit is for the purpose of
revealing to the fullest extent the markings of the butterfly.
Evidently there is here an ample field for further investigation
before definite conclusions are reached.
LIST AND SHADOW OBSERVATIONS
Another field for most interesting studies upon the habits of living
butterflies has been opened up by the very interesting discussion of
_list and shadow_ in Colonel G. B. Longstaff's fascinating book,
"Butterfly Hunting in Many Lands." He there summarizes his numerous
observations upon butterflies in various localities which he has seen
to lean over at a decided angle when they alight. He defines "_List_"
as "an attitude resulting from the rotation of the insect about its
longitudinal axis, as heliotropism results from a rotation about an
imaginary vertical axis at right angles to this." The name is adapted
from the sailors' term applied to a vessel leaning to one side or
another in a storm.
Apparently this interesting habit was first called to the attention of
European entomologists by an observation of Colonel C. T. Bingham
made in 1878, but not published until long afterward. The observation
was this:
"The _Melanitis_ was there among dead leaves, its wings folded and
looking for all the world a dead, dry leaf itself. With regard to
Melanitis, I have not seen it recorded anywhere that the species of
this genus when disturbed fly a little way, drop suddenly into the
undergrowth with closed wings, and invariably lie a little askew and
slanting, which still more increases their likeness to a dead leaf
casually fallen to the ground."
Long before this was printed, however, a similar habit had been
observed by Scudder in the case of our White Mountain butterfly
(_Oenis semidea_). But this species is so exceptional in its habitat
that the habit seems to have been considered a special adaptation to
the wind-swept mountain top. The possibility of its being at all
general among the butterflies in lowlands seems to have been
overlooked.
The observations recorded by Longstaff relate chiefly to various
members of the Satyrid group. For example, a common Grayling, _Satyrus
semele_, was watched many times as it settled on the ground. As a rule
three motions are gone through in regular sequence: the wings are
brought together over the back; the forewings are drawn between the
hind wings; the whole is thrown over to right or left to the extent of
thirty, forty, or even fifty degrees.
This habit, of course, is of advantage to the insect. It seems
possible that the advantage might be explained in either of two ways:
first, the leaning over on the ground among grasses and fallen leaves
might help to render the disguising coloration of the insect more
effective, the large ocelli serving to draw the eye away from the
outline of body and wing; second, the listing of the butterfly toward
the sun tends to reduce the shadow and to hide it beneath the wings.
There is no doubt that when a Grayling butterfly lights upon the
ground in strong sunshine the shadow it casts is more conspicuous than
the insect itself and the hiding of this might be of distinct
advantage in helping it to escape observation. It is significant that
in England the butterflies observed appear to lean over more
frequently in sunshine than in shade. An observation of Mr. E. G.
Waddilove, reported by Colonel Longstaff, is interesting in this
connection:
"A Grayling settled on a patch of bare black peat earth, shut up its
wings vertically, and crawled at once some two yards to the edge of
the patch to where some fir-needles, a cone or two, and a few brittle
twigs were lying, and then becoming stationary threw itself over at an
angle of some forty-five degrees square to the sun. It thus became
quite indistinguishable from its surroundings."
Apparently, some of the Angle-wings may have the same habit, for in
Barrett's "Lepidoptera of the British Islands," there is a note in
regard to _Grapta C-album_ to the effect that it is fond of sunning
itself in roads, on warm walls, or on the ground upon dead leaves in
sheltered valleys. "Here, if the sun becomes overclouded, it will
sometimes close its wings and almost lie down, in such a manner that
to distinguish its brown and green marbled under side from the dead
leaves is almost impossible."
Here is a most fascinating opportunity for American observers to
determine definitely the facts in regard to our numerous species of
butterflies that may show this habit. An observer with a reflex type
of camera might easily be able to get pictures that would be of great
value in helping to determine the principal facts in regard to the
subject. Our common Graylings and numerous species of Angle-wings are
so abundant and easily observed that they offer splendid opportunities
to any one who will undertake a serious study of the subject.
PARASITIC ENEMIES
All three of the earlier stages of butterflies--egg, larva, and
chrysalis--are subject to attack by various parasitic insects which
develop at the expense of the host. Such parasites are probably the
most important check upon the increase of butterflies, and along with
birds, mammals, and bacterial diseases, they help to keep up that
balance of nature which in the long run maintains a surprising
uniformity in the numbers of each kind of butterfly.
For the most part these insect parasites are small four-winged flies,
although many of them are two-winged flies. In either case the life
stages show a series of changes much like those of the butterflies
themselves. Each parasite exists first as an egg, second as a larva,
third as a pupa, and fourth as an adult fly. The larval stage,
however, is simply that of a footless grub which lives within the body
of its victim absorbing its life blood and gradually killing it.
The parasites of butterfly eggs are legion. They are tiny flies whose
life-story in briefest summary is this: The butterfly lays an egg. The
parasite fly finds this egg soon after it is laid, and pierces the
shell with her tiny, sharply pointed ovipositor and deposits inside of
the shell her own microscopic egg. This egg within the egg soon
hatches into a curious little larva that develops at the expense of
the contents of the butterfly egg shell, and soon absorbs the whole
of them. The parasite larva now changes to a pupa which a little later
changes again to an adult fly like the one that laid the parasite egg
in the beginning. Of course the butterfly egg never hatches into a
caterpillar.
One of the most interesting questions in regard to these egg parasites
is this: How does the tiny parasitic fly find the newly laid egg? One
would think that the proverbial search for a needle in a haymow would
be an easy task compared with that of a fly about as large as the head
of a pin finding a butterfly egg of similar size upon some part of one
of the millions of leaves upon the trees and shrubs in field and
forest. Yet the search is successful, as every one who has tried to
get caterpillars from eggs found out of doors will testify. On a later
page in this book, in connection with the story of the life of the
Mourning Cloak butterfly, I have recorded some observations upon the
little parasite which seemed to have been riding around upon the body
of the butterfly waiting for her to lay her eggs.
For one parasite upon the eggs of butterflies, there probably are
dozens that attack the caterpillars. A large proportion of the
butterfly larvae brought in from outdoors, especially those which are
half-grown or more, will yield not butterflies but parasites. This is
the experience of practically every one who attempts to rear these
insects, and it emphasizes the value of the advice that in order to
get fine specimens, it is desirable to rear them from eggs laid by
butterflies beneath netting or in cages.
The life-histories of the parasites that attack caterpillars vary
greatly. The simplest are those of the large Ichneumon flies: The
mother fly lays an egg beneath the skin of the caterpillar. The egg
hatches into a larva that absorbs the fatty parts of the body of the
caterpillar, gradually growing larger and larger until at last it
reaches a length of possibly an inch. By this time it is likely to
have absorbed so large a part of the inside of the caterpillar that
the latter dies. The parasite larva now changes to a pupa, either
inside or outside the skin of the caterpillar, and a little later
changes again to an adult Ichneumon fly.
[Illustration: Tachinid Parasite: _a_, fly; _b_, puparium,
magnified.]
In the case just given, one egg only was deposited within the skin of
the caterpillar. In many others, however, a large number of eggs may
be so deposited by a single fly. A special group of Ichneumon flies,
called the Microgasters, contains many parasites that have this
peculiarity. The Microgaster larvae on coming forth from the
caterpillar have the habit of spinning tiny cocoons within which they
change to pupae. By collecting some cabbage worms which are nearly
full grown, and keeping them in a glass jar one can generally get a
considerable number of these Microgaster cocoons and rear the flies
from them.
Another group of caterpillar parasites is still more minute. They are
called the Chalcid flies. Their life-histories are full of interest,
and might easily furnish opportunity for a long lifetime of study and
experiment. One is likely to get hundreds of these Chalcid flies from
a single caterpillar.
Another interesting group of parasites is that of the two-winged
Tachina flies (_see cut on this page_). The life-story of some of
these is comparatively simple: a buzzing fly, looking much like a
large housefly, lays a small whitish egg upon the skin of a
caterpillar. This egg is glued tightly and is large enough to be
readily seen by the unaided eye. It hatches into a tiny larva that
eats its way through the part of the shell glued to the caterpillar's
skin, and through the latter at the same time. So the newly hatched
Tachina larva finds itself in the body of its caterpillar host. It
lives there, absorbing the fatty juices around it until at last it
either kills or stupefies its unfortunate victim. It has then become
full grown as a larva, and its last larval skin hardens into a brown
pupa-case within which the little creature changes into a pupa. It may
or may not have burrowed through the skin of the caterpillar before
this happened. A little later the pupa changes to a Tachina fly which
breaks apart the pupa-case and flies out into the world.
It has lately been found, however, that many Tachinids have much more
complicated life-histories than this. I have already discussed some of
the more important of these in my book entitled, "Seeing Nature First"
(_pages 150-158_).
One can frequently rear parasites from the chrysalids of butterflies,
but in many cases it is probable that these began their parasitic
development in the caterpillars, which were able to change to
chrysalids before being killed. In some cases, however, the chrysalids
seem to be attacked, especially by certain Ichneumon flies.
REARING BUTTERFLIES FROM CATERPILLARS
There are few things in the world more interesting to watch than the
wonderful changes which a moth or butterfly goes through in the
course of its life. You find on a tree or shrub a worm-like
caterpillar. You take it in charge, placing it in a box or jar where
you can provide leaves for its food and soon it either spins around
itself a silken shroud, thus hiding from your sight, or else it simply
seems to change to a lifeless object without eyes or wings or legs,
unable to move about and motionless, save for a slight wriggle when
you touch it. Yet if you keep the shroud or the mummy-like object for
two or three weeks you are likely to see a beautiful moth come from
the shroud or a glorious butterfly break out of the mummy case. (_See
plate, page 49._) So you can get the realest kind of moving pictures
by simply bringing in the caterpillars that are easily found in
garden, field, and wood.
To collect these caterpillars it is only necessary to be provided with
a pair of sharp eyes and an empty coffee can or some other form of tin
box. Go out into the garden or along the borders of the woods. Look
carefully. If you see places where leaves have been eaten, search the
leaves near by and you are likely to find one or more of the
caterpillars that caused the injury. Transfer them to the box and take
them home with a few leaves of the food plant. There place them in
some form of vivarium, which simply means a box or cage in which you
can keep living creatures.
The most satisfactory cages for rearing caterpillars are those which
are open above so that there is not even a glass plate between the
observer and the insect. This kind of vivarium is easily made by using
a band of some sticky substance like the tree tanglefoot with which
trees are commonly banded, or a strip of sticky fly paper. Any wide
shallow box may be used by simply placing an inch-wide band of the
sticky material around the vertical sides near the top. The
caterpillars will be free to move all over the open box but they
cannot cross the band to escape. Fresh leaves are easily placed in the
open box and the withered ones removed.
The same plan may be adopted with wide glass jars, like the ordinary
battery jar. Choose a rather large one and smear the inner side near
the top with a band of sticky material. The caterpillars are thus
prevented from crawling out, but they are open to observation at all
times. (_See plate, pages 48-49._)
In the case of the caterpillars that change to butterflies no soil
need be placed in the bottom of the jar as these will attach their
chrysalids to the sides or to a stick or board which may easily be put
in. In the case of many caterpillars that change to moths, however, it
is desirable to place about two inches of soil in the bottom of the
jar. Then if the caterpillars are not cocoon spinners they can burrow
into the soil when they are ready to change to pupae.
Instead of applying the sticky material directly to the glass a strip
of sticky fly paper may be glued to it.
As a rule the butterfly caterpillar easiest to find lives upon
cabbages. Go into the garden and you are likely to see a dozen green
caterpillars upon as many cabbage plants. Bring in several of the
larger ones and place them in a vivarium with some fresh cabbage
leaves. In a few days some of them will be likely to fasten themselves
to the vertical sides of the vivarium and shed the caterpillar skin.
Each thus becomes a chrysalis. About ten days later this chrysalis
skin will break open and a white Cabbage butterfly will come out.
So your caterpillar goes through the four different stages of insect
life. It was first an egg laid upon the leaf by a butterfly; the egg
hatched into the caterpillar or larva; the larva changed to the
chrysalis; the chrysalis changed to the butterfly or adult insect.
One of the most satisfactory ways to rear the caterpillars of
butterflies is to get the females to lay their eggs upon the food
plant. In the case of many species this is not difficult. The simplest
way is to enclose the mother butterfly in a small gauze bag tied over
the branch of the food plant. If she has eggs ready to deposit she is
very likely to lay them under these conditions. After they are laid
the mother butterfly may be allowed to escape, but it is well to
replace the gauze protection as a safeguard against many sorts of
enemies which may destroy the eggs or the young caterpillars that
hatch from them. Another way is to enclose the butterflies with a twig
of the food plant in a glass jar, sealing it tight to prevent the
leaves from wilting. The butterfly is likely after she has quieted
down to lay her eggs upon the leaves. According to William G. Wright,
who speaks from his long experience with the butterflies of the West
Coast, these genera will lay their eggs on anything: Parnassius,
Argynnis, Euptoieta, Neonympha, and all members of the family
Satyridae. In these cases one can get the eggs by simply enclosing the
butterflies in glass jars or gauze nets without even the leaves of the
food plant. William H. Edwards found in his long experience that one
can get the eggs of practically all butterflies in confinement,
provided only the insects are sufficiently mature so that the eggs are
ready to be laid. He found that the cause of failure to get eggs from
many of the Fritillaries early in the season was that the eggs were
not mature and that from the same kinds of butterflies with which he
failed early in the summer he got plenty of eggs in September.
There is here a rich field for observation and experiment for every
naturalist who wishes to take up the study of butterflies. He can be
sure of the parentage of the caterpillars and can trace them from the
very moment of egg-laying through all their wonderful changes until
they become butterflies again.
PHOTOGRAPHING BUTTERFLIES
There is a famous old saying that to make hare stew it is first
necessary to catch your hare. So if one wishes to make perfect
pictures of butterflies it is first necessary to get the caterpillars.
For though caterpillars are not butterflies they are butterflies in
the making and they will show you most interesting stages in nature's
manufacture of these dainty and exquisite creatures. This is not,
however, the chief reason why the photographer should get them. He
will wish to make perfect pictures and in order to do this he must
have not only perfect specimens but living butterflies which are
willing to look pleasant while he makes comparatively long exposures
under conditions of light that he can control. If you catch a
butterfly outdoors and bring it in you will be likely to find that it
is by no means a docile subject. The sunlight shining through the
nearest window will be a call which you cannot counteract and your
butterfly will constantly respond to it in a most vexing manner. So
you must catch the butterfly young and take advantage of a brief but
docile period in their lives when they are willing to pose before your
camera in quite a remarkable manner. This is the period just after
the butterfly emerges from the chrysalis when its wings are fully
developed but before the tissues have hardened and the muscles in the
thorax are strong enough for flight. At this time the butterfly is
perfect, every scale is in its place and every spot of color is at its
best, and it will rest quietly upon a flower, leaf, or twig while you
adjust the camera and expose the plate. From one such specimen one can
get many pictures upon different flowers and with different angles of
view. (_See plates, pages 160, 225._)
In order to make admirable photographs of living butterflies it is by
no means necessary to have a regular photographic studio. If one has a
room lighted from the north or east one can arrange for exposure near
the window, using cardboard reflectors to make the light more even
from both sides. In such a situation one soon learns the exposure
periods required and can easily get many beautiful photographs.
A collection of prints of the butterflies of one's locality would be
one of the most interesting photographic exhibits that an amateur
could select. It is comparatively easy to get rather full sets showing
the life-histories of several of our larger species and such sets are
of course of especial interest. In the case of those caterpillars
which make nests upon the food plant, like the Painted Beauty larva
which remains for weeks feeding upon the leaves of the common wild
everlasting, the taking of the pictures of the different stages is
comparatively easy. One can keep the plant with the stem in water, and
get the caterpillar to change to the chrysalis, and emerge as the
butterfly, in the nest made from the flower heads and the upper
leaves.
[Illustration: _From a drawing by W. I. Beecroft_ _See page 59_
THE BLACK SWALLOWTAIL
Caterpillar, chrysalis and butterfly]
[Illustration: Two hundred Monarchs resting on one dead limb]
[Illustration: _Photographed by Craig S. Thomas_ _See pp. 16, 235_
"When a stick was thrown into the tree the air was full of
Monarchs"
A MIGRATION OF MONARCH BUTTERFLIES]
[Illustration: _See page 45_
THE IMPROVED OPEN VIVARIUM]
[Illustration: _From a photograph from life by A. H. Verrill._
_See page 14_
THE CYNTHIA MOTH AND THE COCOON FROM WHICH IT CAME]
BUTTERFLY COLLECTIONS
There are few groups in Nature which offer such advantages to the
collector as that of the butterflies. They are easily obtained, easily
preserved, and retain their beauty for a long period even under
exposure to strong light. They offer opportunities for serious study
in which one cannot only review the facts which others have already
discovered, but also hope to contribute something of value to the sum
of human knowledge.
The mistake most commonly made by beginners with butterflies, as with
other collections, is to undertake too much. Instead of starting on
the hopeless task of making a collection of the butterflies of the
world, it is much better to start with the intention of making a
collection of those of one's own town. In the latter case one can hope
soon to attain the desired end and then, if one wishes, it is a simple
matter to reach out and make a collection of the butterflies of the
state or even of the particular region in which the state is located.
The natural limitations for a collection in New England is to make a
collection of New England butterflies. There is a splendid example of
such a collection on exhibition in the museum of the Boston Society of
Natural History. This contains representatives of practically every
kind that has been collected in New England, and yet there are less
than a hundred species in all. So it is apparent that a local
collection should be attainable by any enthusiastic student and the
very fact that the number of species is limited adds interest and
satisfaction to the pursuit.
The main value of any collection of objects lies in the point of view
of the collector. The most natural point of view for a beginner is
that of the local fauna, as indicated in the previous paragraph. Such
a collection best serves as a basis for a study of the subject but it
may well lead to a broader field through some special phase of
scientific interest. Thus while it would be hopeless for most persons
to attempt a collection of the butterflies of the world it would be
entirely reasonable for one to start a collection of all the species
in the world of any given genus or tribe, and such a set of specimens
would soon come to possess decided scientific value. Or, instead of
the point of view of generic or family relationship, one could take
the point of view of special geographical distribution. Thus a
collection of all the butterflies found within a certain number of
degrees of the North Pole showing the circumpolar butterfly fauna
would have great scientific interest.
There are also various other points of view which could be followed in
making a collection. There are already in many of the museums of the
world collections of butterflies which illustrate the various phases
of true mimicry--the resemblance of one species to another in the same
region. This is a field in which one could spend a lifetime of
endeavor, and secure results of great value to the world of science.
An easier problem for most collectors in the United States would be a
collection made from the point of view of resemblance to environment,
including such examples as the Angle-wings that show a bark-like set
of marks on the under surface. Yet another point of view would be that
of hibernation, the making of a collection of all butterflies that
hibernate as adults.
These are only a few suggestions. There are many other phases of
butterfly life which could be utilized as the basis for interesting
collections. The important thing is to have a definite object in view
and to make the collection a basis for a real study of the subject, so
that the collector will not only be growing intellectually but will
also be making a real contribution to our scientific knowledge.
_Collecting Apparatus_
To collect and preserve butterflies in proper condition for study,
certain apparatus is necessary. Perhaps the first essential is the
collecting net for catching butterflies in the field. The simplest way
to obtain this is to buy it of the dealers in entomological supplies.
Nets in considerable variety and at various prices are offered in the
catalogues of these firms. One can make, however, a net at home with
little difficulty. One need only obtain an iron wire about one fifth
of an inch in diameter and bend it into a circular ring a foot or
fifteen inches wide, leaving the ends projecting at right angles to
the circle and having a blacksmith weld them together so as to form a
spur about four inches long. Now thrust this spur into some convenient
handle, such as a broomstick, and sew over the wire circle a bag of
mosquito netting, Swiss muslin, or some similar fabric. It is better
that this material be green or black rather than white.
After the butterflies are caught, they must be killed, so some form of
killing bottle is necessary. Most collectors use a cyanide bottle, in
which the fumes of cyanide of potassium kill the insects. One of the
best ways to make this is to place in a wide-mouthed bottle two or
three lumps of cyanide of potassium, approximately an inch across.
Over this place some fine sawdust and on top of the sawdust, pour
liquid plaster of paris carefully so that it will harden into a layer
about half an inch thick. Allow the plaster to become thoroughly dry,
then insert the stopper into the bottle and it will be ready for use.
It is better to use a ground glass stopper so that the bottle will
always be air tight. The sawdust is often omitted, the plaster of
paris being poured directly over the cyanide. The special advantage of
the sawdust is that it tends to absorb the cyanide in case it
liquefies, as it often does in damp weather. As this cyanide is a
deadly poison, it is better to let a druggist prepare the bottle or
else to buy it already prepared of the dealers in such supplies.
[Illustration: Butterfly Envelopes. Fold first on line _AB_;
then on _AD_ and _CB_; then on _BF_ and _EA_. (From Holland).]
After the specimens have been killed in the cyanide bottle, some
method of keeping them is necessary. The simplest way is to preserve
them with their wings closed together in pieces of paper folded over
into triangles as indicated on the accompanying diagrams. Such
specimens may be kept for an indefinite time and if one wishes to
mount them later, it is only necessary to place them for a few hours
in a relaxing jar, which is simply a closed vessel with enough water
in the bottom to saturate the air with moisture. A great advantage of
keeping the specimens in these paper covers is that they require so
little room and are easily stored away in tin cans or boxes where they
are safe from dust and destroying enemies.
[Illustration: Setting Board with Butterfly in place.
(From Holland)]
Those butterflies which are to be preserved in the ordinary way, in
drawers or cabinets, must be spread out and held in position while the
body is drying so that the wings will remain expanded. For this
purpose, some form of a setting board is necessary. These may be
bought of dealers or made at home. One of the simplest kinds consists
of two thin strips of pine board, a foot or more long, nailed to end
pieces with a space between the two boards wide enough to accommodate
the bodies of the butterflies. Beneath this open space, a piece of
thin cork is tacked. The pin on which the butterfly is fastened is
pushed through the cork until the wings of the insect are level with
the boards. The wings are then brought forward with a needle point
until they are in the desired position and they are then held in place
by pieces of glass or by bits of cardboard fastened down by pins. The
butterflies must be left in this position until thoroughly dry.
[Illustration: Drying Box for Setting Boards. (After Riley)]
Special insect pins should be used for butterflies. These are longer
than common pins and have rounded heads. They are offered for sale by
entomological dealers. Instead of pinning the insects and preserving
them in cabinets, one may keep them in the Riker mounts, which have
the advantage of being sealed so that there is no chance for dust or
museum pests to reach the specimens. If one wishes to collect
extensively, one will need a considerable number of setting boards and
it will be worth while to prepare for them a special drying box like
that shown in the picture above.
PART II
THE TRUE BUTTERFLIES
SUPERFAMILY _Papilionoidea_
The great suborder of butterflies is commonly separated into two
principal groups called superfamilies. One of these includes all of
the higher butterflies and is named _Papilionoidea_. The other
includes the lower Skipper butterflies and is named the
_Hesperioidea_. The former are characterized by small bodies and
relatively large wings, straight clubbed antennae, and the fact that
the caterpillars do not make cocoons when preparing for the chrysalis
state.
The most authoritative classifications of butterfly families are based
upon the peculiarities of wing venation and are admirably discussed in
such books as Holland's "Butterfly Book" and Comstock's "How to Know
the Butterflies." Without attempting to go into the technical details
of structure it will suffice here to give the list of families which
compose the superfamily _Papilionoidea_:
The Parnassians. _Parnassiidae._
The Swallowtails. _Papilionidae._
The Whites, Orange-tips, and Yellows. _Pieridae._
The Nymphs. _Nymphalidae._
The Satyrs or Meadow-browns. _Agapetidae._
The Heliconians. _Heliconidae._
The Milkweed Butterflies. _Lymnadidae._
The Long-beaks. _Libytheidae._
The Metal-marks. _Riodinidae._
The Gossamer-wings. _Lycaenidae._
It must not be thought that such a list necessarily indicates the
degrees of development of the respective families, for this is not
true. It is simply a linear arrangement adopted for convenience by
leading authorities, notably Dr. Harrison G. Dyar in his standard
"Catalog of American Lepidoptera."
THE PARNASSIAN BUTTERFLIES
FAMILY _Parnassiidae_
It is perhaps a bit unfortunate that the group of butterflies, which
is commonly chosen to head the list of families, is one that is rarely
seen by most collectors. The Parnassians are butterflies of the far
north or of high elevations in the mountains. The four species
credited to North America have been collected in Alaska and the higher
elevations of the Rocky Mountains, so there is very little probability
of any of them being found in the Eastern states.
While, structurally, these butterflies have a close affinity with the
Swallowtails, one would never suspect it from their general
appearance. Their bodies are large and all of the wings well rounded,
so that there is more of the suggestion of a large moth than of the
Swallowtail. The coloring is also more moth-like than with most
butterflies, the wings being very light colored and nearly
transparent, with markings of gray and brown, arranged in dots and
splashes.
All our species belong to the genus Parnassius. The caterpillars show
their affinity with those of the Swallowtails by having the curious
scent organs or osmateria just back of the head. They feed upon such
alpine plants as stonecrop and saxifrage and are well adapted by their
structure and habits to the bleak surroundings of the mountain tops.
As a typical example of the environment in which these butterflies
live, we may take the alpine valleys of such mountain regions as
Pike's Peak. Prof. M. J. Elrod has described a visit where, at an
altitude of 11,500 feet in the month of August, _Parnassius smintheus_
was flying by thousands, and the earlier stages were so abundant that
a water ditch had the surface covered as far as one could see with the
dead or dying caterpillars. In such situations, where ice forms at
night, and snow frequently falls by day, these butterflies develop
apparently in greater numbers than almost any of our other species are
known to do in warmer regions.
THE SWALLOWTAILS
FAMILY _Papilionidae_
This is probably the most distinctive family of all our familiar
butterflies. Its members are characterized by being on the whole the
largest butterflies in our region and by having the hind wings
prolonged into curious tail-like projections, suggestive of those of a
swallow. In general, the basal color of the wings is blackish though
this is commonly marked in various striking ways with yellow, green,
or blue, while the margins of the wings are commonly adorned with red
or orange spots. These butterflies are also characterized by certain
peculiarities in the branching of the wing veins which will be found
pictured in more technical works.
The caterpillars of these butterflies have the characteristic form
pictured on the plate of the Swallowtails opposite page _80_. When
full grown they are large, fairly smooth-bodied worms, showing at most
on the surface sparse fine hairs or fleshy threadlike projections.
Their most characteristic feature is found in the scent organs called
_osmateria_ situated in the back just behind the head. These are
thrust out, generally, when the caterpillar is disturbed and appear as
orange Y- or V-shaped organs from which an offensive odor is commonly
given off. They are supposed to serve the purpose of preventing injury
by enemies, possibly birds, monkeys, and other vertebrates.
Structurally, they are like long tubular pockets that can be turned
inside out. When the pocket is in place it is getting a pocketful of
odors. When it is inverted it lets these odors free. On this account
Professor Comstock has aptly called these caterpillars "the polecats
of the insect world."
When ready to pupate, these Papilio caterpillars spin a web of silk
upon some more or less flattened surface and a loop of silk near by.
They entangle their hind legs in the former and keep their heads
through the latter so the loop supports the body a little behind the
head. Then they change to chrysalids which are held in place by these
sets of silken threads.
The chrysalids are rather large and angular and generally take on
colors approximating their surroundings. They vary so much in
different species that one familiar with them can recognize the
chrysalis and know the kind of butterfly it will produce.
=The Black Swallowtail=
_Papilio polyxenes_
While the Black Swallowtail is not so large as some other members of
the group, it is probably the best known to most people. It is found
throughout many months of the year in practically all parts of North
America south of Canada, and has the habit of flying freely about
fields and gardens in search of flowers from which to suck its nectar
food, and of plants on which to deposit its eggs. The female
butterflies have a remarkable ability in selecting only members of the
great family Umbelliferae for this purpose. In consequence the
caterpillars are generally to be found feeding upon carrots, parsnips,
parsley, and various wild species belonging to this order. (_See
plates, pages 48 and 64-65._)
The eggs of the Black Swallowtail are laid one in a place upon the
leaves of the food plant. Each egg is a small, yellowish, smooth, and
ovoid object. It may often be found by watching the butterflies as
they fly low in search of umbelliferous plants, and seeing one stop
for a minute or so while she lays the egg.
About ten days after the egg is laid it hatches into a small black
caterpillar marked in a characteristic fashion with a blotch of white
in the middle of the body which is suggestive of a saddle. The
caterpillar immediately begins to feed upon the green substance of the
leaf, continuing thus about a week before the first moult. At this
time it does not change much in appearance, still being a spiny
creature blackish in color and marked by the curious white saddle. A
little later it moults again, retaining its original coloring. At each
moult, of course, it gets larger and feeds more freely upon the celery
or other plant on which it may happen to be.
When the caterpillar becomes about half grown it takes on a very
different appearance from that of its early life. The skin is smooth
rather than spiny, and the general colors are green, black, and
yellow. The ground color of the skin is green, which is marked with
black cross-bands along the middle of each body ring. On these bands
there are many large dots of orange yellow, the whole coloring giving
the insect a very striking appearance, especially when it is placed by
itself against a plain background. When they finally become full grown
in this larva state, these caterpillars are almost two inches long.
The larvae of the Black Swallowtail have certain characteristics in
which they differ from many other caterpillars. After each moult they
do not devour their cast skins, which happens in the case of many of
their relatives. When feeding, as well as when resting, they remain
exposed upon the leaf and seem never to attempt to conceal themselves,
as is the habit with a large proportion of caterpillars. It is
probable that this instinct for remaining exposed to view bears some
relation to the curious means of protection possessed by this as well
as other Swallowtail caterpillars. When disturbed one of these larvae
will push out from just back of the head the strange-looking,
orange-yellow Y-shaped organ which gives off a very disagreeable odor.
These osmateria organs are generally believed to be defensive against
the attack of birds and various other enemies, although they seem not
to be effective against insect parasites.
The full-grown caterpillars are likely to leave their food plants when
ready to change to the chrysalis state. They wander in various
directions until suitable shelter is found. A piece of board, a fence
post, or possibly the bark of a tree will answer for this purpose.
Here the caterpillar spins a mat of silk in which to entangle its hind
legs and a short distance away near the front end of the body it spins
a loop of silk attaching the ends to the support. These serve to hold
the chrysalis in place during this helpless period. After the loop is
made the caterpillar keeps its head through it so that the loop holds
the insect in position a short distance back of the head. It is now
ready to moult its last caterpillar skin and become a chrysalis.
One who has watched hundreds of these caterpillars go through this
change, Miss Mary C. Dickerson, describes the process in these words:
"In this final moult the chrysalis has to work very hard. The bulk of
the body is again slipped forward in the loosened caterpillar skin, so
that this becomes tensely stretched over the anterior end, and very
much wrinkled at the posterior end. The skin splits back of the head
and is forced back by its own taut condition and by the efforts of the
chrysalis, until only the extreme posterior end of the chrysalis is
within it. Then the chrysalis withdraws this posterior end with its
many very tiny hooks, from the skin on the dorsal side, and, reaching
around, securely fastens the hooks into the button of silk. Then the
old skin is removed both from its fastening to the chrysalis and from
its attachment in the button of silk."
A short time after the caterpillar's skin has thus been cast off the
chrysalis takes on a brownish color which as is so often the case is
likely to vary somewhat according to the tint of the surrounding
surfaces. This is doubtless a protective device and helps the insect
to escape attack by birds during the long period of exposure. For this
butterfly passes through the winter only in the chrysalis condition,
and the larva which went into the chrysalis in September does not come
out as a butterfly until the following May or June. There are,
however, two broods of the butterflies in the North and at least three
in the South. As the adults live for about two months and there is
considerable variation in the periods of their development it happens
that one can find these Black Swallowtail butterflies upon the wing
almost any time in warm weather, either North or South.
=The Giant Swallowtail=
_Papilio thoas_
The largest of our North American butterflies is a magnificent insect
with a wing expanse of some four inches and with a rich coloring of
black and yellow more or less suffused with greenish or bluish
iridescence that gives it a striking beauty as it flies leisurely
about from flower to flower or stops to lay an egg upon some bush or
tree. The tails are long and expanded toward the tip, their prevailing
color being black with a broad splash of yellow near the end. In a
general way we may say that the upper wing surface is black marked
with two bands of orange-yellow, while the under surface is yellow
marked with two bands of black. (_See plate, page 64._)
The Giant Swallowtail is a tropical species which is abundant
throughout the Southern states and during recent years seems to have
been gradually extending its northern range. It is now commonly found
as far north as forty-two degrees latitude, from Nebraska eastward. In
New England it is occasionally taken in Connecticut, Massachusetts,
and even in Maine, but its appearance in this region is exceptional.
In the orange-growing regions of the Southern states the caterpillars
of this butterfly feed freely upon the leaves of citrus fruits and
they are often called "orange puppies" or "orange dogs." Probably
their curious appearance and their habit of resting for long periods
upon leaf or twig gave rise to this name. In the region indicated the
life-history of the insect may be summarized thus:
The mother butterfly deposits the eggs singly upon the young growth of
orange or other citrus fruit trees, generally near the tips of leaves
or branches. About a week later each egg hatches into a caterpillar
that feeds upon the young leaves, resting upon the lower surface when
not eating. After a few days of this feeding the caterpillar becomes
too large for the skin with which it was born and it moults, coming
forth with a new skin which soon hardens so that it can begin feeding
again. A week or so later it moults for the second time, and continues
these processes of feeding and moulting until full grown, which is
perhaps a month from the time of hatching from the egg. At first the
caterpillars eat only the succulent young leaves and branches, but as
they grow larger they feed more freely upon the older foliage. They
are very voracious and when abundant may often do much damage
especially to young trees. When ready to change to the chrysalis each
caterpillar attaches itself by silken threads to the bark of the
trunk or branch of the tree. Here it changes to a chrysalis which
takes on a color so similar to that of the bark that the insect is
surprisingly difficult to discover. A fortnight or so later it changes
again into a fully developed butterfly that sallies forth in search of
the nectar of flowers. (_See plate, page 240._)
These "orange dogs," like the caterpillars of other Swallowtail
butterflies, have curious yellow scent organs which, when the
caterpillar is disturbed, protrude from the upper surface just behind
the head. These give forth a very disagreeable odor which is believed
to serve the purpose of repelling birds and possibly other enemies. It
has been noticed that these caterpillars are not molested by birds
although they are attacked by various insect enemies. Each mother
butterfly is known to be able to deposit four or five hundred eggs and
it has been suggested that the injuries of the caterpillars may be
checked by shooting the butterfly upon the wing with cartridges loaded
with small bird shot. In the South there are several broods in a
season.
The life-history of this species in more northern regions differs in
the choice of the food plant and the number of broods. It feeds upon
various members of the rue family, including common rue and prickly
ash, as well as upon certain poplars and probably other trees. It is
two brooded and apparently winters as a chrysalis. The butterflies of
the first brood come from the chrysalis about the last of May and are
found on the wing during June. Those of the second brood come from the
chrysalis about the last of July and are found on the wing during
August and September. The length of time required from the laying of
the egg to the emergence of the butterfly varies greatly with the
locality and the temperature. It commonly extends over a period of
four or five weeks.
[Illustration: _From a drawing by Mary E. Walker_ _See page 62_
GIANT SWALLOWTAILS
Visiting blossoming branches of the orange tree. (Reduced)]
[Illustration: _See page 59_
BLACK SWALLOWTAIL VISITING THISTLE, SHOWING THE TONGUE
PARTIALLY UNCOILED]
[Illustration: _Photographed from life_ _See page 83_
IMPORTED CABBAGE BUTTERFLY
(A good deal magnified)]
[Illustration: _See page 65_
THE BLUE SWALLOWTAIL
Upper surface above; lower surface below]
=The Blue Swallowtail=
_Laertias philenor_
The Blue Swallowtail is said to have closer affinity with the splendid
butterflies of the tropics than most of our other Papilios. The sheen
of metallic color upon its wings is certainly suggestive of the broad
expanse of similar colorings in the gorgeous butterflies from South
America. This species is easily recognized by the general blackness of
the front wings and the basal parts of the hind ones as seen from
above, about two thirds of the area of the latter being overlaid with
blue-green scales that give the metallic lustre characteristic of the
species. Near the outer border of the basal half of the front wings
there is a row of about five rather indistinct whitish spots, this row
being continued more distinctly on the hind wings. On the under
surface the white spots of the front wings are more pronounced than on
the upper, while each hind wing is brilliantly marked with about seven
large orange spots, part of them fringed on one or both sides with a
distinct margin of white. The extreme side borders of all four wings
are distinctly marked with white crescents and the fringes on the
tails as well as more or less of the darker fringes of the hind wings
are of a beautiful purple color. In the males each hind wing has along
the inner border a slender, pocket-like depression which is said to be
the seat of the scent organs. (_See plate, page 65._)
This splendid butterfly is a southern species. It is found from the
Carolinas to California, being at times extremely abundant in certain
localities over this great region. It seldom occurs as far north as
New England and in a general way east of the Rocky Mountains its
northern limit approximates that of forty-three degrees of latitude.
It varies considerably in size and differs greatly in abundance in
different localities and different seasons.
[Illustration: Caterpillar of the Blue Swallowtail.
(After Riley)]
Probably the commonest food plant of the caterpillars is the
Dutchman's Pipe or Aristolochia, which is frequently planted as an
ornamental vine for porch adornment. It also feeds upon wild ginger or
Asarum and probably upon other plants. A dozen or more eggs are laid
upon a leaf by the mother butterfly, usually in a cluster or grouped
near together. They hatch a week or so later into small brownish
caterpillars which remain together for awhile in little groups that
feed side by side upon the leaf, beginning at the margin and working
toward the centre. As they become larger they feed more freely and
gradually disperse so that each forages for himself. As they approach
maturity their appetites become voracious and their presence is often
shown by the defoliated condition of the branches. They have back of
the head the osmateria or scent organs which are commonly found in
the other caterpillars of this genus, but the odor emitted by them is
likely to be less pronounced than usual.
[Illustration: TWO OF THE SWALLOWTAILS
(Three fourths natural size)
The Palamedes (_see page 76_)
The Giant (_see page 62_)]
[Illustration: _See page 67_
THE GREEN-CLOUDED SWALLOWTAIL
Upper surface above; lower surface below]
When full grown the caterpillars find such shelter as they may and
each spins a bit of silken web and a silken loop which hold it while
it changes to the chrysalis. This chrysalis is very likely to take on
the colors of the immediate surroundings and thus be rather difficult
to see. If the egg was laid by one of the spring or early summer
butterflies, the chrysalis will soon change to a butterfly which will
appear toward midsummer and which may lay eggs for another brood of
caterpillars. These caterpillars mature to chrysalids the same season
and some of them are believed to change into butterflies in autumn,
these butterflies hibernating through the winter; while others are
believed to remain unchanged through the winter and disclose the
butterfly the following spring. This is an exceptional condition for
the Swallowtails and it is worth while to make careful observations
along its northern limits to learn more definitely the facts as to the
winter condition.
=The Green-clouded Swallowtail=
_Papilio troilus_
This beautiful butterfly is essentially a southern species and is
found over a wide range of territory from the Mississippi River to the
Atlantic Ocean. It occurs as far north as New Hampshire and Vermont
and has even been reported from Alberta, Canada. It is easily
recognized by the blue-green clouding of the upper surface of the
wings, the general color being velvety black with distinctive rows of
yellow spots along the margins of the front wing. These spots are
present also on the hind wing where they are almost changed to blue
because overlaid with a general cloudiness of this color. On the under
surface of the hind wings there are two rows of orange-brown spots,
the inner row being nearly crescent-shaped and the outer row oblong.
In the living insect the tail projections on the hind wings are
usually twisted into a vertical plane at right angles to the plane of
the wings.
The caterpillars of this species feed upon the leaves of sassafras and
spice bush. The distribution of the butterfly appears to be closely
related to the distribution of these plants.
As is the case with so many of our Swallowtail butterflies, the
Green-clouded Swallowtail passes through the winter in the chrysalis
stage. Late in spring the butterflies emerge and soon afterward lay
their eggs singly upon the leaves of sassafras or spice bush. The eggs
soon hatch into lead-colored caterpillars, largely covered with spiny
warts. Each caterpillar cleverly makes a protecting nest by eating out
a narrow strip in the leaf which frees a flap along the margin that is
turned back upon the leaf, making a case in which the larva lives. It
spins a silken carpet on one side of the case and rests upon this
carpet when at home. During its feeding periods it goes outside and
eats the tissues of the other parts of the same leaf. It continues to
occupy this first nest for a week or more by which time the rest of
the leaf is likely to be pretty well consumed.
Having passed the first moult and thus become larger and having
practically eaten itself out of its first house and home the
caterpillar now crawls to a larger leaf where it proceeds to make a
more enduring structure. In this case it does not need to bite a
channel along one side of the midrib as it did before, but instead it
begins to spin silken threads transversely across the upper surface in
such a way as to fold over the border of the leaf and make a tubular
chamber in which it has plenty of room to move about. It uses this as
its home for some time thereafter, wandering out at evening to feed
upon neighboring leaves as its hunger necessitates. In this way it
continues to feed and grow for a week or two. Then it finds it
necessary to construct still another home, which it does by bringing
together the opposite sides of a leaf, taking care to have a door-like
opening at the base of the blade next the leaf stalk. This third home
serves it to the end of its larval existence. It goes in and out as
necessary, remaining concealed when it casts its skin and until the
body tissues harden afterward. Apparently it devours the cast skin and
thrusts the hard covering of the head out of the nest. Consequently
these little homes are clean and sanitary and serve admirably their
protecting purpose.
The full-grown caterpillars have the curious appearance of those of
the other Swallowtails. The third ring behind the head is greatly
swollen, making, with the rings directly in front of it, a
characteristic picture suggesting a grotesque face with large eye-like
spots at the top. The general color is green, darker above than below,
and there are six rows of blue dots along the body. (_See plate,
page 80._)
When ready to change to the chrysalis, the caterpillars desert their
leafy homes and on a twig or board or stone each spins a bit of silken
webbing and a silken loop. They now change to chrysalids which are
likely to resemble the color of the background and which are somewhat
smoother than many of the Swallowtail chrysalids. About two weeks
later the butterflies emerge.
_The Eclosion of the Butterfly_
The transformation of a chrysalis into a butterfly is always one of
extraordinary interest. Comparatively few definite descriptions of
this process have been given by careful observers. One of the best of
these is that written by Mr. Scudder in connection with the emergence
of this butterfly, and it is so accurate and complete that it seems
worth while to quote it at length:
"The butterfly generally emerges from the chrysalis early in the day,"
writes Mr. Scudder, "and the first signs of the immediate change are
strong forward and backward movements of the chrysalis at intervals of
a few seconds; perhaps the third or fourth attempt will be successful,
when a click may be heard at the distance of several feet; but all the
subsequent movements are absolutely noiseless, though rapid; at
intervals of three or four seconds, spasmodic movements similar to the
first carry on the process; first the split continues along the
thorax; then it runs down either side between the legs and wings,
ultimately to the tips of the antennae. As this progresses, the
actions become more strenuous and more frequently repeated; with eager
efforts the butterfly pushes forward its half-detached head; now an
antenna springs from its case, at once assuming its natural attitude;
the other soon follows, and then the wings are partially drawn from
their sheaths, and while in this position seem to be used as levers or
arms to aid in withdrawing the rest of the body; next the legs appear,
seize the upper part of the chrysalis skin, and speedily withdraw the
whole body. It is now a curious-looking object, the wings wrinkled
and bloated, and, although the whole process of escape lasts little
more than half a minute, already twice the size of the sheaths they
lately occupied. The insect crawls upward until it finds a secure
resting place, and there remains until ready for flight; each half of
the tongue, drawn independently from its receptacle, is rolled in a
separate spiral, and now while the wings are gradually expanding the
insect applies all its energies to uniting their two parts,
incessantly rolls and unrolls them, and beginning simultaneously at
the base, gradually fits them together by their interlocking joints;
in about fifteen minutes all but the tips are perfectly united; these
require nearly fifteen minutes more, and are not fairly interlocked
until the wings are fully expanded, nearly a full half hour after the
escape from the chrysalis; the wings, however, are still tender, and
generally require two hours to stiffen. When at last the insect
ventures upon flight, it is not with an uncertain flutter, but boldly
and steadily, as if long accustomed to the action."
The butterflies of this second brood of the season are likely to begin
to appear early in August, continuing to become more abundant
throughout that month. These lay eggs upon the same food plant and the
caterpillars grow to maturity in the same way as those of the first
brood. They become full grown during September or October, and then
change to chrysalids which remain dormant until the following spring.
The species thus has two broods each year and passes the winter only
in the chrysalis state.
These beautiful butterflies are likely to be found in the sort of
situations where the food plants of the larvae are growing. Open
groves, the borders of woods, and the margins of streams or marshes
are the places where one is most likely to find spice bush and
sassafras. These are the places to look for these butterflies which
one may often see in graceful flight near the ground, pausing now and
then to seek a sassafras leaf or to sip the nectar from a flower.
=The Tiger Swallowtail=
_Papilio glaucus_
One of the many things that make a study of the life-histories of
butterflies of great interest is the variations in the development of
many of the species. One who follows the simplest life-story of a
butterfly and sees the egg change to larva and the larva change in
size and form and color with each successive moult and then change
again into the seemingly inert chrysalis, from which there finally
comes the winged butterfly--unlike the egg, unlike the larva, unlike
the chrysalis--a creature of perfect beauty, wonderfully adapted to
living freely in the air and sipping ambrosial nectar from the
flowers--one who follows these changes with awakened vision can
scarcely fail to have a sense of wonder as to the laws that govern
such intricate phenomena. But the marvel is still more pronounced in
the case of those butterflies which have two or more forms arising
from the same lot of eggs in a way which science has as yet not
adequately explained.
The splendid Tiger Swallowtail is an example of this dimorphism which
is of especial interest because of the fact that the extra form is
confined to one sex and to only a part of the geographical area over
which the butterfly is found. The species occurs over a very large
part of the North American continent, being found from ocean to ocean
and from Canada to Florida. In the region north of approximately the
fortieth degree of latitude there is but one form of the insect--the
familiar yellow-and-black striped butterfly which every one has seen
visiting the lilac blossoms in May or June. South of this, however,
part of the females take on an entirely different appearance, being
almost wholly black with the hind wings touched with lines of blue and
bordered with crescents of yellow and orange. The curious thing about
it is that a certain mother butterfly may lay a dozen eggs part of
which will develop into the usual yellow form and the rest into the
black form, both lots being of the same sex. This black form is so
entirely distinct in appearance that the two were originally described
as separate species, and they were long considered such, until
breeding experiments determined the precise condition. (_See plate,
page 17._)
This species is of interest also for another reason. The caterpillars
during their later life are remarkable examples of that curious
resemblance to the head of a serpent which is thought to have a real
protective value in frightening away attacking birds and possibly
other enemies. The rings of the body just back of the head are much
swollen and on the top of the swollen part there are two large
circular marks which bear a striking resemblance to eyes. When the
insect is at rest it withdraws its head and holds up the front of the
body in such a way as certainly to suggest at the first glance that
one is looking at the head of a small snake, an impression which is
likely to be enhanced when the caterpillar pushes out the curious
yellow scent organs from the ring near the top of the head, these
organs taking on the forked appearance of a snake's tongue.
Obviously it is exceedingly difficult to get definite observations
under natural conditions to determine whether these seeming
resemblances are really of value to the caterpillar in frightening
away birds or other enemies. About the only direct evidence which I
have come across upon this point is found in this paragraph by Dr. J.
L. Hancock:
"When I recall the first sight of this larva, the impression gained of
it was a most curious one. The forward mask-like face was remarkably
startling. This mask, bearing eye-like spots and the light transverse
ridge, gave it an aspect which might easily be mistaken for real eyes
and a mouth. This contrivance is only a false face in no way connected
with the real eyes and mouth. One might imagine the shock that a bird,
or other predaceous enemy, would experience when looking upon this
grinning mask. This is in reality the effect produced, for I have seen
small birds so alarmed that they lost their appetite and curiosity for
these larvae after a brief glance at them. It is certain that these
singular markings have the effect of terrifying their bird
enemies."[B]
[B] "Nature Sketches in Temperate America," p. 146.
The yearly cycle of the Tiger Swallowtail is much like that of the
related species. It passes the winter as a chrysalis, the butterflies
coming forth just about the time that the lilacs bloom. They remain
upon the wing for a few weeks and deposit their eggs upon a great
variety of trees and shrubs, for the food plants of the larvae are
unusually varied and include tulip trees, birches, wild cherries,
apples, poplars, ash, and several other common trees or shrubs. These
eggs soon hatch into caterpillars that feed upon the leaves and make
for themselves resting places by spinning a web of silk transversely
across the surface of the leaf. They remain upon these silken webs
when not feeding and in later life are likely to cause the leaf on
which the web is made to curl into a partial tube. When fully
developed they change to chrysalids which give forth the summer brood
of butterflies in July and August. These in turn lay eggs for the
caterpillars which change to chrysalids in autumn and remain in that
condition until the following spring.
=The Short-tailed Papilio=
_Papilio brevicauda_
Were one enough of a magician to make one butterfly over into another
it would be comparatively easy to take a Black Swallowtail and
transform it into this species. One would only need to trim off the
long tails so that they project very slightly from the angles of the
hind wings and to change the yellow spots to orange. He would thus
accomplish what Nature through the long ages seems to have
accomplished in a limited northern area in Newfoundland and around the
Gulf of St. Lawrence, for the Short-tailed Papilio is confined chiefly
to this region, where it lives a life very similar to that of the
Black Swallowtail. The caterpillar feeds upon the leaves of various
members of the parsley family and is said to have learned to warm
itself during the middle of the day by resting upon stones and gravel
which have absorbed the sun's heat rays. Presumably there is but one
brood a year and the insect hibernates as a chrysalis.
=The Palamedes Swallowtail=
_Papilio palamedes_
If the magician who had succeeded in converting a Black Swallowtail
into the Short-tailed Papilio wished to try his hand on making a
Palamedes Swallowtail he could not do better than to use again the
same black butterfly. He would only need to make it about one half
larger, retaining practically all its color markings and the outline
of its wings and tail. For this species bears a remarkable resemblance
to the Black Swallowtail, seeming to be a giant variety induced by the
warmth of the southern climate where it lives, and possibly by the
more generous supply of the magnolia and sassafras leaves upon which
the caterpillars feed.
This species is distinctly a southern form occurring as far west as
the Mississippi River throughout the more Southern states. As one
would expect in the long seasons and warm climate of this region there
are several broods each year and the caterpillars often hibernate as
well as the chrysalids. The adult butterflies are lovers of the sun
and are said to roost at night upon the tops of live oak and palmetto
trees.
=The Zebra Swallowtail=
_Iphiclides ajax_
Most of our Swallowtail butterflies are so distinctive in form and
colors that they are easily distinguished from one another, but the
Zebra species is so different from all the rest that when it is once
seen it is likely always to be remembered. The striking combination of
green and black stripes with very long tails, set off by beautiful
crescents of blue and of red, at once distinguishes this fine
butterfly in any of its varying forms.
Three distinct forms of this species occur, namely:
_Marcellus_, the early spring form, small in size with short tails,
that show white only on the tips;
_Telamonides_, the late spring form, somewhat larger, with tails a
little longer and showing more white on the outer half;
_Ajax_, the summer form, decidedly larger with tails very long.
It would be a comparatively simple matter to understand these forms if
they were simply seasonal variations, with three broods, each form
succeeding the other as the season advances. But this is far from
being the case. We have instead the most complicated and confusing
series of conditions imaginable--conditions for which no one has yet
given satisfactory explanations.
To make a fairly clear statement of what happens, suppose we assume
that we start with twenty over-wintering chrysalids. In April ten of
these disclose their butterflies which are Marcellus, the early spring
form. In May the other ten disclose their butterflies which are
Telamonides, the late spring form. We thus have these two forms,
appearing successively in spring from the same set of over-wintering
chrysalids.
After flying about for a short time the Marcellus or early spring
Swallowtails lay eggs upon the leaves of papaw trees or bushes. These
eggs soon hatch into caterpillars that feed upon the leaves and grow
rather rapidly. A little more than a month later they mature into
butterflies which are Ajax, the summer form.
In a similar way the Telamonides or late spring butterflies lay eggs
soon after they appear, also upon papaw leaves, and these eggs in
about a month mature into Ajax, the summer form.
So we have Ajax, the summer form, developing directly from both the
early spring or Marcellus and the late spring or Telamonides
butterflies.
These Ajax butterflies in their turn lay eggs for caterpillar young.
These soon mature into a brood of butterflies which are of this same
Ajax form. There may be successive broods through the summer,
practically all of them being this same Ajax summer form.
The last brood of caterpillars, however, change to chrysalids which do
not disclose the butterflies until the following spring. And then the
first that come out are the Marcellus form and the last the
Telamonides form. So we may have these two forms maturing from the
same brood of autumn caterpillars.
This seems a sufficiently complicated life-history to suit the most
persistent solver of puzzle problems, but there is an additional
factor which adds much to the possible confusion of the broods. In
each brood of caterpillars from the earliest to the latest there are a
certain number of chrysalids which remain dormant through the
remainder of the season and the following winter, maturing into
butterflies the next spring. Consequently at the end of every winter
there are a miscellaneous lot of chrysalids which represent every
brood of caterpillars that lived the previous season, and all of these
develop into either Marcellus or Telamonides butterflies.
Such a condition of affairs certainly represents what an old New
Englander would be likely to call a "mixed-up mess," and it is
difficult for science to find rhyme or reason to explain it. It speaks
eloquently for the perseverance of W. H. Edwards that he was able with
infinite patience through years of study and experiment to untangle
this intricate web of butterfly existence.
While the preferred food plant of this species is papaw, the
caterpillars are also known to feed upon the spice bush and upland
huckleberry. When full grown these caterpillars are about two inches
long and of a general pea-green color, banded transversely with yellow
and black, and having an especially conspicuous band of this sort on
the third ring behind the head. The scent organs are protruded when
the larva is disturbed and emit an offensive odor. The chrysalids are
green or brown according to the surroundings.
The Zebra Swallowtail is a southern butterfly found as far west as
Texas and the Rocky Mountains and having its northern limits in a zone
ranging approximately from Massachusetts to Nebraska. It is especially
abundant in the Southern states east of the Mississippi River.
Mr. S. F. Denton found this species abundant in southern Ohio where
the females laid their eggs upon the small papaw bushes. They selected
the leaves of these bushes for sleeping quarters, "clinging to the
under side of the leaves where early in the morning they might be
taken with the fingers."
_Other Swallowtails_
Several other Swallowtail butterflies are found within the limits of
the United States, especially in the Far West and along the southern
boundaries. Some of these occasionally migrate east or north so that
they are collected in the Central states. Thus _Papilio daunus_, _P.
oregonia_, and _P. zolicoan_ are all found in the "List of Nebraska
Butterflies," published by Mr. H. G. Barber, and the same species have
been taken in other states in or near the Mississippi Valley. These
and various others are described and pictured in Dr. Holland's
excellent "Butterfly Book."
_Synopsis of the Swallowtails_
_Tiger Swallowtail_: _Yellow form_ (_Papilio glaucus turnus_). Expanse
3 1/2 to 5 inches. Upper surface of wings bright yellow with each
black margin marked with a row of yellow spots. Both sexes throughout
its range. _Black form_ (_Papilio glaucus glaucus_). Black all over
with blue markings on outer half of hind wings and row of straw-yellow
crescents on borders of same. Females only, and only south of about
latitude 40 degrees.
_Giant Swallowtail_ (_Papilio thoas_ or _Papilio cresphontes_).
Expanse 4 to 5 1/2 inches. Upper surface black with two bands of
yellow starting at the inner margin of the hind wings and coming
together as a row of yellow spots at the outer angles of each front
wing. A yellow spot on each black tail. Under surface yellow.
_Zebra Swallowtail_. Expanse 3 to 3 1/2 inches. Easily known by the
stripes of green upon black and the long, slender tails. The different
forms vary in size and in the length of the tails. Scientific names
are: Early Spring Form, _Iphiclides ajax marcellus_; Late Spring Form,
_I. ajax telamonides_; Summer Form, _I. ajax ajax_.
[Illustration: _From a photograph from life by A. H. Verrill_
_See pages 7, 67_
CATERPILLARS OF THE GREEN-CLOUDED SWALLOWTAIL
In various stages of growth]
[Illustration: _Photographed from life_ _See page 83_
IMPORTED CABBAGE BUTTERFLY]
[Illustration: _Photographed from life_ _See page 215_
BLUE-EYED GRAYLING VISITING JOE PYE WEED
(Magnified)]
_Green-clouded Swallowtail_ (_Papilio troilus_). Expanse 3 1/2 to 4
inches. Black with about seven yellowish spots on outer margin of each
front wing and eight marginal spots on each hind wing, those at the
ends of row orange, the rest yellowish or bluish. Outer half of hind
wings clouded with greenish blue. Under surface black with two
distinct rows of yellowish spots on front wings and two rows of orange
spots on hind wings.
_Blue Swallowtail_ (_Laertias philenor_, often called _Papilio
philenor_). Expanse about 4 inches. Black or brownish black with most
of hind wings showing a bluish green iridescence. A row of marginal
spots on each hind wing, more or less distinct on the front wings.
Outer fringe with broad white markings interrupted by black ones.
Under surface of each hind wing with seven large orange spots, some
with partial borders of white.
_Black Swallowtail_ (_Papilio polyxenes_ or _Papilio asterias_).
Expanse about 3 inches. Black with two conspicuous rows of yellow
spots on outer half of wings, more distinct in males. On hind wings
rows of blue spots or splashes between the yellow ones. Orange-red
circle with black centre at inner angle of each hind wing. Under
surface with markings more distinct and more orange-yellow.
_Short-tailed Swallowtail_ (_Papilio brevicauda_). Much like the Black
Swallowtail but generally smaller, with very short tails, and with the
yellow markings more or less changed to orange. Confined to the
limited region of Newfoundland and the lands bordering the Gulf of the
St. Lawrence.
_Palamedes Swallowtail_ (_Papilio palamedes_). Expanse 4 to 4 1/2
inches. Much like the Black Swallowtail but considerably larger. A
curved yellow line on the head back of each eye. Found only in the
South.
THE WHITES, ORANGE-TIPS, AND YELLOWS
FAMILY _Pieridae_
The most familiar and abundant American butterflies are classified
together under the family name _Pieridae_, or the Pierids. Three
groups or tribes of them are popularly known as the Whites, the
Orange-tips, and the Yellows. Our two commonest butterflies, the White
or Imported Cabbage Butterfly and the Sulphur Yellow Butterfly, are
typical representatives of this family. Most of the rest, like these,
are of moderate size with rounded wings which are more or less marked
with black. There are six well-developed legs and the caterpillars of
practically all the species are cylindrical greenish worms which under
a lens are seen to be covered with short hairs. When the caterpillars
are ready to change to chrysalids they spin a web of silk upon the
supporting surface and just back of it, a loop of silk that serves to
hold the chrysalis in place and keep it from swaying back and forth.
The chrysalids are characterized by having a pointed projection on the
front of the head, the rest of the body being more or less angular.
Notwithstanding their close general resemblance to their food plants,
the caterpillars of this family suffer from attack by various enemies.
Birds find many of them, not only eating them themselves but also
using them freely for feeding the nestlings. Parasitic insects also
take a heavy toll from these caterpillars. This attack of enemies is
doubtless a chief reason why many of the common species are not much
more destructive.
THE TRIBE OF THE WHITES
Three white butterflies of approximately the same size are found
widely distributed over the United States. The most abundant species
is the White or Imported Cabbage butterfly. The next in abundance is
probably the Checkered White, and the rarest in most localities is the
Gray-veined White which is a northern form.
=The White or Imported Cabbage Butterfly=
_Pieris rapae_
There is probably no butterfly which one can generally find so easily
in its early stages as the White or Imported Cabbage butterfly which
is found practically wherever cabbages are grown and is generally so
abundant that caterpillars and chrysalids are readily discovered. In
the Northern states the insect passes through the winter within the
chrysalis, coming forth rather early in spring as the familiar white
butterfly with black dots upon the wings and blackish front angles of
the fore wings. (_See plates, pages 64-65 and 81._)
The butterflies that thus appear in spring flit freely about over
fields, meadows, and gardens, sipping the nectar of various early
flowers through their long, coiled tongues and stopping occasionally
to alight upon the leaf of a cabbage or other plant of the mustard
family to deposit the small, pale yellow eggs which remain attached by
a sort of glue. The adult butterflies continue their leisurely life
for a fortnight or more, thus extending the laying of the eggs over a
considerable period.
About a week after being deposited the egg hatches into a tiny green
caterpillar that begins feeding upon the tender surface of the cabbage
leaf. It is commonly called the cabbage worm and it is doubtless the
most generally destructive insect affecting this crop. It continues to
feed for several days before the first moult, after which it becomes
decidedly larger and begins to eat again more voraciously than before.
It undergoes several successive moults during the next two or three
weeks before it becomes full grown as a caterpillar. Unlike most
butterfly larvae it has changed very little in its general appearance
during its growth. It is always of a pale green color, strikingly like
the glaucous green of the cabbage leaf, a fact which doubtless helps
to conceal it from the eager eyes of birds and other animals.
When the caterpillar is thus full fed it is likely to leave its food
plant and find shelter elsewhere. Sometimes it will stop on the lower
surface of the outer leaves, but more commonly it will find a piece of
board, an overhanging stone, a fence-post, or the side of a building,
where it will prepare for the change to the chrysalis. It will do this
by spinning a silken thread upon the surface in which to entangle its
hind legs and a loop of silk near by with which to hold its body. When
these preparations are completed the insect will cast its last
caterpillar skin, emerging as a grayish or brownish chrysalis, the
color usually varying with the color of the surrounding surface.
A week or more later the chrysalis skin bursts open and the white
butterfly emerges to expand and dry its wings before it flies away for
its leisurely life. There are two or more broods each season, the
number varying with the latitude. There is a decided variation in the
length of time required for the completion of the cycle from egg to
butterfly. In hot weather the insect may mature in about three weeks
while in cooler weather it may require as much as five weeks.
_Its Introduction and Dispersal_
While it is well known that a large proportion of our most destructive
insects have been imported from Europe, it is only in comparatively
few cases that man has been able to make careful records of the times
and places where the insects were introduced and to follow the spread
of the pest from these original centres. The Imported Cabbage
butterfly is one of the few species of which this is true. This insect
has been known for centuries in Europe, where it feeds freely upon the
leaves of cabbages and turnips. So far as known it was first
introduced into North America about 1860, when it appeared in Quebec.
Eight years later it was again introduced into the region of New York
City. From these two points the insect spread gradually in various
directions until in 1871 it covered the whole of New England and
various parts of New York and New Jersey. From then on it spread even
more rapidly and was evidently accidentally introduced into various
parts of the country which became new centres of distribution. Of
course it would be very easy for this to happen through the shipment
of cabbages from one part of the country to another. Within thirty
years of the time of its first introduction it had become a serious
pest over practically all the United States and Canada.
The introduction and spread of such a pest is of interest in itself,
but in this case there is to be noted the additional fact that the
presence of this foreigner has practically led to the extinction of
two native species of butterflies, both closely related to each other
and to the invader and both feeding upon the same plants. An almost
pure white butterfly--the Gray-veined White--was formerly exceedingly
abundant in many of the Northern states, while farther south there was
another species, the Checkered White, which was also abundant. Both of
these have now so completely disappeared that in some localities they
are almost never seen, while their imported relative has become
perhaps the most abundant of all American butterflies.
=The Gray-veined White=
_Pieris napi_
One would naturally suppose that when a butterfly was reduced to the
greatest possible simplicity in its coloring there would be little
chance for the development of geographical or seasonal varieties. But
he would only have to study a large collection of specimens of this
species, taken at different seasons and in different regions, to find
his supposition at fault. Here is a butterfly which is essentially a
slender black-bodied creature with four white wings scarcely touched
with color, and yet we are told that there are eleven varieties in the
United States so distinct that they have received scientific names,
not to mention various others which have been found in Europe. This
is indeed a remarkable showing and it is a striking illustration of
the infinite variations which Nature can produce with the most limited
materials.
To me the seasonal variations of a butterfly are always of greater
interest than those which are geographical. We know that in the case
of a great many animals, from insects to mammals, the different
conditions of climate and physical environment found in different
regions produce variations of many sorts. So it does not seem
especially strange that in Alaska there should be a different form of
a certain butterfly than is found in Virginia. But that in the same
locality there should be two or more forms of a butterfly existing
under identical conditions as to climate and environment is not so
easily explained. In the case of the Gray-veined White we collect in
early spring in New England, or other Northern states, a lot of
chrysalids. We keep them until the butterflies come forth and we find
even here two distinct forms, one smaller and more delicate than the
other, with both surfaces of the wings pure white: scientists call
this form, _virginiensis_; the other larger with the under surface of
the wings slightly tinted with yellow: scientists call this form
_oleracea_. The first named has but one brood a year while the second
lays eggs which develop into caterpillars that produce butterflies of
still a _third_ form, in which the upper surface of the wings is pure
white with a slightly greater expanse: scientists call this form
_cruciferarum_. These three varieties occur in Eastern regions and may
be found in the same localities, and differ considerably from various
geographical varieties found in the Far West.
The caterpillar of the Gray-veined White is a bit smaller than those
of the nearly related forms, and in color is green with no distinct
longitudinal markings, but with many fine dots of black over the
surface. The cylindrical body is covered with a fine down. When
feeding upon cabbage it is more likely to attack the outer than the
inner leaves, and so even when abundant it is less troublesome to
gardeners than the imported species. It is now, however, so rare that
it seems to feed chiefly upon wild cruciferous plants and is more
likely to be found along the borders of open woods than in gardens and
fields. The winter is passed in the chrysalis state.
=The Checkered White=
_Pontia protodice_
Some years ago the Checkered White was commonly called the Southern
Cabbage Butterfly but the general distribution of the imported species
has had the same effect upon its abundance in the South that it has
had upon the Gray-veined White in the North. Consequently, it is now
much less abundant than formerly, even in the Southern states where it
is most at home. There are two fairly distinct forms: the spring form
and the summer form. The latter is practically of the same size as the
Imported Cabbage Butterfly: the males have the hind wings nearly white
above and the fore wings with a few black dots or spots upon their
outer halves. The females are much more definitely marked, having the
upper surface of both pairs of wings marked in black or brownish black
in such a way as to enclose a large number of white diamonds. The
spring form is decidedly smaller and the markings are much less
distinct than in the summer form.
The seasonal history of this species is comparatively simple. In
winter the chrysalids are found. From these chrysalids in early spring
the small butterflies of the spring form come forth. These lay eggs
upon various cruciferous plants which hatch into greenish caterpillars
that eat the leaves and soon mature so far as their caterpillar stage
is concerned. They are then about an inch long, with downy cylindric
bodies more or less marked with rather pale yellow stripes, touched
here and there with purplish green or dotted slightly with fine black
dots. These caterpillars now attach themselves by means of a button of
silk and a silken loop to some support like a piece of board, the side
of a stone, or almost any available shelter. Each casts its larval
skin and appears as a grayish chrysalis from which probably a
fortnight later the summer form of the butterfly emerges. There are
commonly two broods of this summer form, making three sets of
butterflies for the entire season. The caterpillars of the second
summer brood of butterflies go into the chrysalis stage in autumn to
remain throughout the winter.
Some very interesting observations upon the sleeping habits of this
butterfly have been made in St. Louis by Mr. and Mrs. Phil Rau. The
insects were found abundantly resting upon the seed heads of white
snakeroot. Early in October, when a warm south wind was blowing, the
great majority of the butterflies slept horizontally with their heads
toward the wind. At other seasons and in other places, many of them
were found in a vertical position but practically all had their bodies
toward the wind prevailing at the time. The observers were unable to
ascertain definitely whether the insects thus oriented themselves at
the time of alighting, so that their wings presented the least
resistance to the force of the wind, or whether this was a mechanical
result of the breezes.
=The Great Southern White=
_Pontia monuste_
There used to be in the Northern states before the advent of the
Imported Cabbage butterfly a familiar white butterfly which then laid
its eggs upon cabbages in much the same way that the imported pest now
does. One who has seen this northern Gray-veined White and then sees
the Great Southern White will be likely to think of the latter as a
larger edition of the former, for in the males of the southern species
the wings are practically white save for a narrow dusky border at the
outer angle of the front pair, although in the female this dusky
margin is wider and the hind wings show a series of dusky triangles
near the margin. There is also a curious black marking suggestive of a
crescent on each front wing near the middle of the front border, which
helps to make the appearance of this butterfly very distinct from that
of any other.
Although this species is at times so abundant that it swarms in great
flocks and although it has been known for many years, its life-history
seems not to have been carefully worked out since it was first
described by Abbott more than a century ago. The caterpillars feed
upon cruciferous plants and when full grown are about an inch and a
half long, of a general yellow color, more or less striped with
purple lines. The species is distinctly tropical extending northward
into our Southern states.
Dr. G. B. Longstaff reports this species as abundant in Jamaica where
he found that the clubs of the antennae of the living insects showed a
beautiful turquoise blue color, although another observer described
them as bright green with a tinge of blue. This is an interesting
color variation for a member of this group. In the tropics also there
are two forms, one belonging to the dry season and one to the wet
season.
_Synopsis of the Whites_
_Imported Cabbage Butterfly_ (_Pieris rapae_). Expanse 2 inches. Upper
surface white with a black marginal dash on the front outer angle of
the front wing. One round black spot on each of the four wings in the
male. Two round spots on each of the front wings in the female and one
round spot on each of the hind wings. Under surface of hind wings
yellowish white; spots on front wings in same position as on upper
surface. A spring form (_immaculata_) is smaller and the black spots
are almost obsolete.
_Gray-veined White_ (_Pieris napi_). Expanse 2 inches. Upper surface
white with only a darker marginal splash next the body. Under surface
white with gray veins.
_Checkered White_ (_Pontia protodice_ or _Pieris protodice_). Expanse
2 inches. Upper surface white, strongly marked especially in the
female with dark grayish brown on both pairs of wings. Along the outer
margins these marks are so arranged as to enclose white diamond spots.
Male with front wings only lightly marked and hind wings scarcely
marked at all. Under surface much like upper, with a slight yellowish
tinge in female.
_Great Southern White_ (_Pontia monuste_ or _Pieris phileta_.) Expanse
2 1/2 inches. General color white with a narrow black margin around
apical angle of front wings. These margins are wider in the female, in
which sex there is a series of marginal spots on the hind wings.
Easily known by its large size.
THE TRIBE OF THE ORANGE-TIPS
When one sees a gossamer-winged butterfly flitting from flower to
flower on a bright June day it seems one of the most ethereal of
earth's visions. One could readily fancy that the whole
sight--flowers, butterflies, and all--might easily vanish into thin
air. So it is something of a shock to hear scientists talk about
fossil butterflies and to realize that these fragile creatures have
been living generation after generation for untold millions of years.
A realization of this fact, however, helps us to understand the many
wonderful ways in which butterflies in all stages of their existence
have become adapted to the conditions of their lives.
There is perhaps no group of butterflies whose beauty seems more
fragile than that of the Orange-tips. These are delicate creatures,
with slender bodies and almost gauzy wings, of a size somewhat smaller
than our common white and yellow butterflies. Perhaps the most
remarkable feature is the marking of the wings, the upper sides of the
front pair having an orange patch near the apex and the under sides
having a background of delicate whitish or yellowish green, lined and
spotted with darker coloring in a very characteristic way. This
peculiar marking is so significant that it has been called "flower
picturing." To understand the reason for its existence one has only to
watch the butterflies in their native haunts. He will find them
flitting from blossom to blossom among the plants of the mustard
family--the _Cruciferae_. This is one of the most characteristic
families in the plant world: the foliage for the most part is small
and delicate and the flowers have a characteristic four-petaled
structure, being practically always of small size and generally toned
in whites or yellows. When an Orange-tip is at rest upon these
blossoms it merges so completely into the background that it
disappears from view. Should a bird chase one of these insects through
the air it would see chiefly the orange tips which are so marked upon
the upper side of the wing, and when the butterfly closed its wings
and lighted among the flowers the orange color would instantly
disappear and there would be only an almost invisible surface against
the background of flower and leaf.
The adaptations of these Orange-tips to the conditions of their lives
are by no means confined to this remarkable resemblance to the flowery
background. In the case of some species the whole yearly cycle has
been adapted to correspond to the yearly history of the cruciferous
food plant. As is well known many species of the mustard family spring
up early in the season, put forth their blossoms which quickly develop
into fruits and then die down, the species being carried through until
the next year by the dormant seeds. In a similar way the Orange-tips
feed as caterpillars upon the host plant through the spring,
completing their growth before the plant dies and then changing to
chrysalids which remain dormant through summer, fall, and winter and
come forth as butterflies early the following spring. The insect has
thus adapted itself in a most remarkable manner to the yearly history
of its plant host.
=The Falcate Orange-tip=
_Synchloe genutia_
The Falcate Orange-tip is about the only member of this tribe
generally distributed east of the Rocky Mountains. This is a beautiful
insect which is sparingly found even as far north as New England. It
is more abundant throughout the Southern states, occurring south at
least as far as Texas. It appears to be a good illustration of the
adaptation of its development to that of its food plants. The eggs are
laid upon leaves or stems of such spring-flowering _Cruciferae_ as
rock cress (_Arabis_), and hedge mustard (_Sisymbrium_). On hatching
the caterpillars feed upon stems, leaves, flowers, and even seed pods
of these plants, becoming mature in a few weeks and changing to
chrysalids under the protection of such shelter as they can find. In
the Northern states these chrysalids remain unchanged until the
following spring when the butterflies emerge and are found upon the
wing for a few weeks in May and early June. In some southern regions
at least the species is evidently double-brooded, as Dr. Holland
reports that he has taken the butterflies in late autumn in the
western portion of North Carolina.
[Illustration: Egg of _Synchloe genutia_, magnified 20
diameters. (From Holland)]
This Falcate Orange-tip is one of the daintiest and most exquisite of
northern butterflies. It is a prize which any collector will find joy
in possessing. It is easily recognized by its general white color,
which in the female is relieved only by a distinct black mark on the
upper surface of the front wings and a row of marginal markings upon
all the wings. The male is slightly smaller and is at once known by
the orange blotch on the outer angle of the upper surface of the front
wing. This outer angle projects into a distinct point which gives the
species its name Falcate. (_See plate, page 256._)
Dr. J. L. Hancock has described in a most interesting manner the way
in which this Orange-tip loses itself among the flowers of rock cress.
In northern Indiana he found this butterfly abundant in April at the
time of the blossoming of _Arabis lyrata_. The butterflies would be
flying about, easily seen in the air. Then they would suddenly
disappear and could be found only after the most careful search. They
had simply lit upon the flower heads, when the flower picturing of the
under surface of the wings blended perfectly with the appearance of
the clustered flower.
"The green markings of the under side of the wing," writes Dr.
Hancock, "are so arranged as to divide the ground color into patches
of white, which blend with or simulate perfectly the petals of the
clustered flowers. The eyes of the butterfly are delicate pale green
and the antennae are whitish, all of which adds to the effectiveness
of the blend. The flowers of _Arabis_ have white petals with the
centre yellowish green, as is also the calyx. There is a shade of pink
outside the base of the petals. All in all, the adaptation of insect
to flower here displayed is one of rare exquisiteness."[C]
[C] "Nature Sketches in Temperate America", p. 83.
Dr. Hancock found that the butterflies were able to cling on the
flowers during strong winds very persistently, so that even when a
storm blew across the sand dunes they were likely to remain in
position. They also have the instinct to rest very quietly after they
have lit upon the clustered flower heads.
=The Olympian Orange-tip=
_Synchloe olympia_
In various parts of the Southern states there is at least one other
Orange-tip butterfly which is found occasionally in connection with
the Falcate Orange-tip. It was named Olympia many years ago by William
H. Edwards. It is a delicate white species marked with black and
yellow very lightly both above and below, the yellow showing only on
the under side of the hind wings and that part of the front wing which
is exposed when the insect is at rest. Strictly speaking, this is not
an Orange-tip because the orange color is lacking in both sexes.
This is rather a rare species which occurs occasionally from the
Atlantic states to the Great Plains south of a line drawn from
northern Maryland to northern Missouri. Like its allies the larvae
feed upon various cruciferous plants, the hedge mustard being one of
these and the adults visit the flowers of the same family. They
doubtless have habits similar to those of the Falcate Orange-tip, and
the extreme delicacy of color must render them practically invisible
when resting upon the small white flowers of most crucifers.
[Illustration: _From a drawing by Mary E. Walker_ _See page 72_
THE TIGER SWALLOWTAIL
(Reduced)]
[Illustration: _From a drawing by W. I. Beecroft_ _See page 83_
THE IMPORTED CABBAGE BUTTERFLY
Caterpillar, chrysalis, and butterflies]
Most of the Orange-tip butterflies are found on the Pacific Slope,
ranging from Alaska southward, several of them being especially
abundant in the western mountain regions. About eight species are
recognized as belonging to our fauna, some of which have several
well-marked varieties.
_Synopsis of the Orange-tips_
_Falcate Orange-tip_ (_Synchloe genutia_, _Anthocaris genutia_ or
_Euchloe genutia_). Expanse 1 2/5 inches. Tips of front wings
projecting in a hooked angle. Orange blotch on upper surface near tip
in male, absent in female.
_Olympian Orange-tip_ (_Synchloe olympia_, _Euchloe olympia_ or
_Anthocaris olympia_). Expanse 1 1/2 inches. Wings white above in both
sexes with greenish black markings at base of all wings and along
front margin of front wings, especially at apex. No orange patch.
THE TRIBE OF THE YELLOWS
A large proportion of our most abundant and conspicuous butterflies
belong to the Tribe of the Yellows. Sometimes it is called the Tribe
of the Red-horns because the antennae of the living insects are so
often red. These insects vary in size from the large Brimstones or
Cloudless Sulphurs, expanding three inches, to the delicate little
Dainty Sulphur, expanding scarcely an inch. The distinctive
characteristics of the tribe are found in the very gradual enlargement
of the joints of the antennae that form the club, and the stout palpi,
the last joints of each of the latter being short.
=The Brimstone or Cloudless Sulphur=
_Callidrayas eubule_
Practically all northern butterflies are variously marked in different
colors, while the butterflies of tropical regions are commonly tinted
in monotone, though often showing a splendid iridescence. One with
very little experience can tell the look of a tropical butterfly and
would be likely to say at once that the Cloudless Sulphur is one of
these. The upper surface of the wings of the male is a clear plain
sulphur with merely the narrowest possible fringe of brown around the
margin made only by the colored marginal scales. The under surface is
lighter and sparsely dotted in brown. In the females the marginal
brown takes on the shape of a series of small crescents and there is a
single round brown eye-spot just in front of the middle of each front
wing.
While the Cloudless Sulphur is without doubt essentially a tropical
species it has an extraordinary geographical range. It is extremely
abundant in Mexico, Cuba, and the tropical zone in South America. It
extends south even to northern Patagonia and north to New England,
Wisconsin, and Nebraska.
Presumably in the tropics this species breeds continuously, one
generation following another in regular succession unless interrupted
by drought or other natural phenomena. In our Southern states there is
more or less interruption by the winter season, so that it is commonly
considered to have only two broods, the butterflies hibernating.
Farther north there is probably only one brood in summer, and perhaps
not even that in the extreme limit of its range. For there is pretty
good evidence that the specimens seen in the Northern states are
migrants from the south, coming singly or in scattered flocks in early
summer, and if they lay eggs the butterflies of the new generation
return south in autumn. But the precise conditions are not well known
and need careful observations in various localities.
The life-story of a generation of these butterflies is much like that
of the other Yellows. The eggs are laid, one in a place, on the
leaflets of various species of wild senna (_Cassia_) and soon hatch
into cylindrical caterpillars that devour the tender leaflets. In a
few weeks the caterpillars mature and change to curious and
characteristic chrysalids. The head projects in the shape of a cone
and the back is so concave as to give the side view of the chrysalis a
very striking appearance.
Like so many of the Yellows this butterfly is sun-loving and social in
its habits. Great numbers flock together, their large size and bright
coloring rendering them very conspicuous. They often alight on the
ground to sip moisture when they have been likened to beds of yellow
crocuses. They also fly long distances in flocks that attract much
attention. It is likely that the northward distribution takes place in
summer through such migrating hosts.
_Other Sulphur Butterflies_
The Large Orange Sulphur is a closely related butterfly of about the
same size, in which the coloring is uniformly orange-yellow instead of
lemon-yellow. It also belongs to the tropics, occurring in our extreme
Southern states and ranging occasionally as far north as Nebraska.
The Red-barred Sulphur is another splendid butterfly, somewhat larger
than the Brimstone, which is easily distinguished by the broad reddish
bar across the upper surface of the front wings. It is tropical but
migrates rarely even as far north as Indiana, Illinois, and Wisconsin.
=The Dog's-head Butterfly=
_Meganostoma caesonia_
The Dog's-head butterfly furnishes one of the most remarkable examples
of accidental resemblance in wing markings that can be found in the
whole order of scale-winged insects. It is comparable with the skull
and crossbones on the back of the death's-head moth. In the butterfly
the middle of the front wings has a broad band of yellow against a
black margin on each side and the yellow outlines make an excellent
silhouette of the profile of a poodle with a large black eye-spot in
exactly the proper place. The females are less brightly colored than
the males but they still show the dog's-head silhouette.
This is a southern species, which occasionally strays as far north as
New York City, New Hampshire, Wisconsin, and Iowa. The larvae feed on
species of Amorpha and are believed to be three-brooded in southern
regions where the butterfly occurs.
The California Dog's-head is even more beautiful than the southern
species. It is remarkable for its pink and purple iridescence--a
characteristic which is not common in the butterflies of the Yellow
and the White Tribes. The silhouette of the Dog's-head is less perfect
than in the more eastern species, and the yellow color tones are more
tinged with orange. The female is strikingly different, the wings
being plain pale yellowish buff marked only with a round blackish
eye-spot near the middle of each front wing and the barest suggestion
of a dark line around the extreme margin.
=The Clouded Sulphur=
_Eurymus philodice_
It is an interesting fact that the butterfly which one is most likely
to find in fields and along roadsides during practically all the weeks
of summer has seldom if ever been noted as a destructive insect. The
Clouded Sulphur is probably the commonest species in its group. There
may be times when the White Cabbage butterfly or other forms are more
abundant, but the Clouded Sulphur retains its place season after
season, with comparatively little noticeable variation in its numbers.
This is doubtless an illustration of an insect which has established
such relations with its food plants and its various insect and other
enemies that it remains in a fairly stable equilibrium--an example of
what is often called the balance of nature.
The Clouded Sulphur is about the only medium-sized yellow butterfly
generally found in the Northeastern states. The adults may be seen
from spring until autumn. They lay eggs upon clover and other plants.
These eggs hatch into small green caterpillars that feed upon the
leaves and are protectively colored so they are comparatively seldom
seen. When the food plant is disturbed they drop to the ground,
crawling up again upon stems and leaves when the disturbance is over.
These caterpillars moult several times during their growth. When full
grown they find such shelter as they are able and each spins a silken
web over part of the surface. It then fastens its hind legs into this
web and later spins a loop near the front end of the body. It pushes
itself beneath this loop and waits for several hours before the skin
breaks open along the back and is gradually shuffled off revealing the
chrysalis in position. A week or two later the fully developed
butterfly emerges from the chrysalis.
These yellow butterflies lend a distinctive charm to our summer
landscapes. They are constantly to be seen fluttering from place to
place, lightly visiting flowers of many kinds from which they suck the
nectar, and gathering in great colonies by roadside pools where they
seem to sip the moisture. There are many references to this insect in
the writings of New England authors. It evidently was an especial
favorite of James Russell Lowell who has often referred to it in
passages like this:
"Those old days when the balancing of a yellow butterfly over a
thistle bloom was spiritual food and lodging for a whole forenoon."
=The Orange Sulphur=
_Eurymus eurytheme_
Were one able to take a Clouded Sulphur butterfly and change the
yellow to a deep orange color he could easily make a specimen that
would pass for the present species. The resemblance is very
remarkable and shows the close affinity between these two beautiful
insects.
Like so many others of this group the Orange Sulphur is essentially a
tropical species. In the eastern United States it is rarely found
north of latitude forty degrees, but south of that it becomes
increasingly abundant as one approaches the tropics. It occurs from
the Carolinas to Texas, and over the great range in which it lives it
takes on many different forms and habits. It is one of the most
remarkable examples of variation in coloring exhibited by any of the
butterflies. Nearly a dozen species names have been given to its
various disguises, all of which are now recognized as synonyms. In the
more northern regions where it is found, only one of these forms
usually occurs, but in other places bright yellow and pale white
varieties are found.
The life-history of this butterfly along latitude forty degrees is
very similar to that of the Clouded Sulphur. There seem to be usually
two broods and the caterpillars live upon leguminous plants,
especially alfalfa, buffalo clovers, wild senna, and other species of
Trifolium and Cassia. Apparently also it hibernates in both the
caterpillar and the butterfly stages.
In the extreme Southwest--as on the plains of Texas--the vegetation
dries up completely in summer so that there is no succulent leafage
for the caterpillars to live upon. In such cases the insect must
aestivate rather than hibernate. This species apparently succeeds in
doing this by having the caterpillars go into a more or less lethargic
condition in which they pass the summer. The adult butterflies utterly
disappear in June and are not seen again until early in autumn when
the autumn rains have started the growth of vegetation anew. The
insects then make up for lost time and produce several broods in rapid
succession.
In the Imperial Valley of California this butterfly is a serious pest
to alfalfa growers. It continues to reproduce throughout a very long
season, one brood following another from March until December, and in
mild winters there seems sometimes to be practically no cessation of
its activities. Mr. V. L. Wildermuth found that the development of a
generation in breeding cages in this valley varied from twenty-two to
forty-four days, the latter in cool, the former in hot weather. The
stages in the first and the third broods in spring varied thus: Egg,
first six days, third four days; larva, first thirty days, third
twelve days; chrysalis, first eight days, third five days. In this
case the first generation extended from March 15 to April 30 and the
third from May 28 to June 20. After the fourth brood of butterflies
there was such an overlapping of the various stages that it was
impossible to distinguish the broods.
=The Pink-edged Sulphur=
_Eurymus interior_
This beautiful butterfly was first made known to the world of science
by Louis Agassiz, the great naturalist who did so much to arouse a
scientific interest among Americans. He found it on a famous
expedition to the northern shores of Lake Superior, which not only
served to bring to light many interesting phases of geological history
but also laid the foundation for the copper mining industry which has
since become so important in that region. The butterfly thus brought
to light has been found to be a characteristic northern species,
occupying a rather narrow belt nearly along the fiftieth degree of
latitude and extending west almost to the Pacific Coast. The species
is occasionally taken as far south as the White Mountains and there
are indications that in this region there are two broods a year. The
male butterflies are known at once by a beautiful pink edge on all the
margins; they bear otherwise a close resemblance to our common Sulphur
Yellow. The females are much lighter in color, often having no black
markings on the upper surface of the hind wings.
=The Black-bordered Yellow=
_Eurema nicippe_
This is essentially a tropical butterfly which has spread out over
most of our Southern states where it is abundant and widely
distributed. It adds a distinct touch of color and life to many
landscapes when the butterflies swarm by thousands upon clover
blossoms and other low vegetation. The eggs are laid upon the leaves
of clover and more especially upon some common species of Cassia, such
as wild senna. Each egg soon hatches into a small greenish cylindrical
worm, colored and striped in such a way that as it rests upon the leaf
it is easily overlooked. This larva develops rapidly and soon becomes
about an inch and a quarter long, being rather slender and fairly
smooth. It now spins a bit of silk upon a twig or some similar support
and also the frailest sort of a silken loop to pass around its back.
It now entangles its hind feet in the bit of silk and soon casts off
its last caterpillar skin, emerging as a curious looking chrysalis
about three quarters of an inch long with a remarkable pointed
projection on the front of the head. When seen through a hand lens
this pointed projection and the well-developed characteristic wing
sheaths give the chrysalis a remarkable resemblance to some of the
twig hoppers or Membracids. The colors vary considerably with the
surroundings but are commonly toned in various shades of green and
yellow brown.
A little later each chrysalis breaks open to disclose one of the
beautiful butterflies.
The conditions under which this butterfly lives at the limit of its
northern range are not well determined. It is probable that many of
those seen here have flown from considerably farther south, and that
these migrants lay eggs from which a brood of butterflies develops,
these native born appearing late in summer. Presumably the latter
hibernate, but whether they can do this successfully under the
rigorous conditions of our northern winters has never been determined.
In fact, Scudder wrote some years ago that no caterpillars had ever
been found in New England. Here is an interesting opportunity for some
young observer to make a real contribution to science.
=The Little Sulphur=
_Eurema lisa_
Were one to imagine a Clouded Sulphur butterfly reduced to half its
usual size and built with a corresponding delicacy of structure, one
would have a pretty good idea of the beautiful little creature called
by the above name. I well remember in my college days taking what was
probably the first of these butterflies ever collected in the region
of our Michigan college. It was a prize that very likely had wandered
north from Indiana but which served to add much glory to the little
collection in which I took such pride, for this is essentially a
southern species. In many regions of the South it is so abundant that
it can be taken by any one. It ranges from coast to coast and extends
south into the tropics. In the eastern region it is found from
southern Wisconsin to southern New England, occurring sparingly and
locally in various places along the line thus indicated.
The food plant of the species is chiefly wild senna or other kinds of
Cassia. The mother butterflies deposit the eggs singly on leaves or
stems, generally on the small leaflets of the compound leaf. Less than
a week later each egg hatches into a cylindrical greenish caterpillar
that feeds upon the leaflets in a characteristic fashion. Instead of
devouring the blade from the margin inward it gnaws narrow strips
between the smaller veins. When not feeding, the caterpillars protect
themselves from observation by birds or other enemies by resting
motionless along the stem of the leaflet or else along the midrib on
the under side. As is well known the leaflets of Cassia, like other
leguminous plants, close at night. It is probably on this account that
these caterpillars feed chiefly by day. The general green color of the
skin and the straight stripe along the side help to make this
caterpillar very inconspicuous when it is at rest.
When full grown the caterpillar reaches a length of three quarters of
an inch. It now finds some bit of shelter on which it spins a bit of
flat web and a silken loop to hold it in place as it becomes a
chrysalis. It then changes and remains quiescent for ten days or more
when it emerges as the dainty butterfly.
Notwithstanding its abundance and its successive broods its
life-history is none too completely worked out. There is still
opportunity for careful observations upon the way in which it passes
the winter in various parts of its range. While in the South it
apparently hibernates as an adult, this fact is not certain in the
more northern localities.
Notwithstanding its diminutive size this butterfly has been known to
swarm in such enormous numbers as to seem a veritable cloud. The most
notable record of this has been quoted by Scudder in connection with a
swarm that invaded the Bermuda Islands, in 1874, on the first day of
October. It was described in these words:
"Early in the morning several persons living on the north side of the
main island perceived, as they thought, a cloud coming over from the
northwest, which drew nearer and nearer to the shore, on reaching
which it divided into two parts, one of which went eastward and the
other westward, gradually falling upon the land. They were not long in
ascertaining that what they had taken for a cloud was an immense
concourse of small yellow butterflies, which flitted about all the
open grassy patches in a lazy manner, as if fatigued after their long
voyage over the deep. Fishermen out near the reefs, some few miles to
the north of the islands very early that morning, stated that numbers
of these insects fell upon their boats, literally covering them."
As is the case with so many of the related yellow butterflies there is
an albino variety of this species. It has been given the variety name
_alba_ although it is really a pale yellow rather than a true albino
form.
=The Dainty Sulphur=
_Nathalis iole_
While the Little Sulphur butterfly seems about as delicate a creature
as one could ask to see, it loses that distinction when it is compared
with the still smaller Dainty Sulphur. The latter expands scarcely an
inch when its wings are stretched apart, and its slender body and
antennae help to give the suggestion of extreme delicacy. There is
more marking of black upon the sulphur-yellow wings than is the case
with the larger form, the upper portion of the front wings showing
only a broad yellow band upon a background of darker color. The under
wings are nearly all yellow.
_Synopsis of the Yellows_
_Brimstone_ or _Cloudless Sulphur_ (_Callidryas eubule_ or
_Catopsilia eubule_). Expanse 2 1/2 inches. Upper surface of male
clear, light, sulphur yellow. Female with a brown spot in front of
middle of each front wing and a narrow brown margin on all the wings.
Under surface deeper yellow with sparsely scattered brownish dots.
_Red-barred Sulphur_ (_Callidryas philea_ or _Catopsilia philea_).
Expanse 3 inches. Easily known by the reddish orange bars on the
sulphur-yellow wings.
_Large Orange Sulphur_ (_Callidryas agarithe_ or _Catopsilia
agarithe_). Expanse 2 1/2 inches. Distinguished at once by its uniform
orange-yellow color.
_Dog's-head Butterfly_ (_Zerene caesonia_, _Colias caesonia_ or
_Meganostoma caesonia_). Expanse 2 1/4 inches. Upper surface yellow
with black inner and outer borders on front wings and black outer
border on hind wings. The black and yellow of each front wing so
combined as to make a distinct dog's head with black eye.
_Clouded Sulphur_ (_Eurymus philodice_ or _Colias philodice_). Expanse
2 inches. Upper surface sulphur yellow with blackish borders, the
yellow brighter in the male than in the female. Male with line between
yellow and black distinct, a black spot just in front of the middle of
each front wing and an orange spot near the middle of each hind wing.
Under surface of male deeper yellow, with spots as on the upper
surface but without black margin, and with a row of sub-marginal
brownish dots on each wing. Female with upper surface more generally
suffused between marginal mark and the yellow part with more or less
duskiness both above and below. Spots on each wing much as in male. In
the white form of the female (_pallidice_) the yellow is replaced by
white.
_Pink-edged Sulphur_ (_Eurymus interior_). At once distinguishable
from _philodice_ by the narrow pink edge of all the wings, showing
both from above and from below, slightly smaller as a rule.
_Orange Sulphur_ (_Eurymus eurytheme_ or _Colias eurytheme_). Expanse
2 1/4 inches. Much like Clouded Sulphur in markings except that
prevailing color-tone is orange yellow.
_Black-bordered Sulphur_ (_Eurema nicippe_, _Xanthidia nicippe_ or
_Terias nicippe_). Expanse 2 inches. Upper surface of wings bright
orange with a small black dash in front of the middle of each front
wing and a broad black border on all the wings. In the females the
borders are interrupted at the rear. Under surface slightly brownish
yellow, minutely striated and clouded when exposed when the butterfly
alights.
_Little Sulphur_ (_Eurema euterpe_, _Eurema lisa_, _Xanthidia lisa_ or
_Terias lisa_). Expanse 1 inch. Easily known by its small size and
delicate structure. Upper surface of wings yellow with distinct black
borders. Under surface yellow with indistinct spots.
_Dainty Sulphur_ (_Nathalis iole_). Expanse 1 inch. Easily known by
its small size and narrow yellow wings with black bars across the
outer angles and black bands across the back border of the front wings
and the front border of the hind wings.
THE NYMPHS
FAMILY _Nymphalidae_
A large proportion of our most familiar butterflies belongs to this
family. The Fritillaries, the Angle-wings, the Sovereigns, and the
Emperors are tribes in which practically all the species are of medium
or large size. The Crescent-spots include a few which are rather
small.
The combinations of characters by which the Nymph family is
distinguished are these: Front legs dwarfed into lappets; scaly
antennae; veins of fore wings not swollen at base; wings of normal
shape, not much longer than wide. Larvae cylindrical, but varying
greatly in form, color, and skin coverings. Chrysalids angular in
most species, in others rounded.
The stories of the lives of the many members of this family vary
considerably, as one would expect from their variety and numbers. We
may take, however, the life of the familiar Antiopa or Mourning Cloak
as typical of the group. Briefly summarized, its story may thus be
told:
During sunny days in spring one may often see a beautiful purple-back
butterfly, having a cream-colored border along the outer margin of its
wings, flying leisurely about, in the vicinity of woods and in the
open fields. This insect is called the Antiopa or Mourning Cloak; it
is represented natural size in plate opposite page 145. It has passed
the winter in this adult condition, having found shelter in some
retreat where it is not directly exposed to the storm and stress of
the weather.
When the leaves of the elm, willow, and poplar trees are nearly
expanded, these butterflies deposit their eggs upon the twigs. These
eggs are laid in clusters encircling the twigs, there being twenty or
more in each cluster. In the act of oviposition, the butterfly keeps
her wings spread out, moving the body and abdomen about as the placing
of the eggs necessitates.
About two weeks after the clusters of eggs are thus laid upon the
twigs of the food plant, they hatch into small blackish caterpillars,
each emerging from the egg shell through a small hole that it eats out
of the upper surface. They thus enter upon the second stage in their
life-history--the larva or caterpillar stage. As soon as hatched, they
crawl to the nearest leaf upon which they range themselves side by
side, with their heads toward the margin of the leaf. They feed in
this position, nibbling at the green surface of the leaf-blade and
leaving the network of veins untouched.
[Illustration: _See page 76_
THE ZEBRA SWALLOWTAIL
Summer form: upper surface, above; under surface, below]
[Illustration: _From a drawing by Mary E. Walker_ _See Page 101_
THE CLOUDED SULPHUR BUTTERFLY
Caterpillar and butterfly on red clover plant. (Reduced)]
[Illustration: _From a drawing by Mary E. Walker_ _See page 76_
ZEBRA SWALLOWTAILS
Visiting blossoming branches of the pawpaw tree. (Reduced)]
[Illustration: _See pages 97-115_
SOME OF THE TRIBE OF YELLOWS
upper surfaces at left; under surfaces at right
(1) The Black-bordered Yellow--male;
(2) the Clouded Sulphur--male;
(3) the Orange Sulphur--female;
(4) the Dog's-head--male]
These caterpillars continue to feed in this manner for about a week,
remaining side by side when feeding, and marching in processions from
one leaf to another as the food supply is exhausted. Wherever they go,
each spins a silken thread on the surface traversed, so that the
combination of all the threads makes a sort of carpet that serves as a
foothold for the caterpillars. At the end of the week they moult or
cast their skins, a process in which the skin of each larva splits
open along the back, and the larva crawls out covered with a new skin
that had been formed beneath the old one. This new skin stretches
somewhat after the caterpillar emerges, so that the insect is able to
increase considerably in size. At the period of moulting, the
caterpillars remain quiet for a short time, but they soon become
active again and begin feeding with increased voracity.
[Illustration: Eggs of Mourning-Cloak, laid in a cluster on a
twig. (From Holland).]
During the next three weeks, this moulting process is repeated three
times, the caterpillars becoming larger each time, and leaving their
cast skins upon the denuded twigs. They soon scatter more or less over
neighboring leaves, but remain in closely associated colonies. As they
increase in size, they eat more and more of the leaf substance; when
half grown, they devour all but the midrib and the side veins; but
when they get larger, only the midribs are left.
The carpet web that they form becomes more conspicuous as the
caterpillars become full grown. They then leave the tree or shrub on
which they have been feeding, and scatter about, seeking some
sheltered situation. Having found this--perhaps beneath a stump or
along the under side of a fence--each caterpillar spins a web of silk
along the surface. It then entangles the hooked claws of its hind legs
in the silken web, and lets its body hang vertically with the head end
curved upward. It remains in this position some hours before the skin
along the back just behind the head splits apart and is gradually
wriggled upward, until finally it is all removed and there hangs in
place of the caterpillar a peculiar object having no definite form.
But it rapidly assumes a definite form--that of the chrysalis--which
is grayish brown, different specimens varying somewhat in shade.
In this quiet chrysalis, the insect is apparently almost as inert as a
mummy. If you touch it it will wriggle a little, but otherwise it
hangs there mute and helpless. On the inside, however, the tissues are
being made over in such a wonderful way that, in about two weeks, from
the mummy case into which the caterpillar entered there comes a
beautiful butterfly.
When this butterfly first breaks through the mummy shell, its wings
are very small, although its body, antennae, and legs are well
developed. By means of the latter, it clings to the empty chrysalis,
while its wings expand. At first these wings are short, but as soon as
the insect takes a position in which the wings hang downward, they
begin to expand, and soon reach full length, but are more or less
crumpled longitudinally, and the front wings are not so wide as the
hind ones, hanging limply inside the latter.
After the butterfly has thus reached its full form and size, it crawls
from the chrysalis to some neighboring support, where it rests quietly
for half an hour or more. During the latter part of this time it
exercises its unused muscles by slowly opening and closing its wings,
until it finally flies away.
THE TRIBE OF THE FRITILLARIES
This is one of the most distinctive tribes of the family of Nymphs.
The clubs of the antennae are about twice as long as broad and
curiously spoon-shaped. The palpi are large and bushy, with the last
joint very short. Most of the species are rather large and practically
all are beautifully mottled in various tones of brown, red, black, and
silvery gray. A large proportion of our midsummer butterflies are
members of this tribe.
=The Gulf Fritillary=
_Agraulis vanillae_
In tropical America there is a genus of butterflies called Agraulis.
These are fairly large insects, approximating the size of the Viceroy,
which show most beautiful colors in the tropical sunshine. One member
of this genus has come north to our Southern states, and is
occasionally found as far up as Virginia and southern Illinois,
extending below this from ocean to ocean. It reveals on its upper
surface the most exquisite t
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