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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.