Chapter I: Part 1

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THE BUTTERFLY GUIDE

THE BUTTERFLY GUIDE

A POCKET MANUAL FOR THE READY IDENTIFICATION OF THE
COMMONER SPECIES FOUND IN THE UNITED STATES AND CANADA

BY

W. J. HOLLAND, LL.D.

Director of the Carnegie Museum
Author of “The Butterfly Book,” “The Moth Book,” etc.

_With 295 Colored Figures_
_Representing 255 Species and Varieties_

Garden City New York
DOUBLEDAY, PAGE & COMPANY
1915

_Copyright, 1915, by_
DOUBLEDAY, PAGE & COMPANY

_All rights reserved, including that of
translation into foreign languages,
including the Scandinavian_

To the
BOY SCOUTS OF AMERICA
I dedicate
this Book
_The Author_

PREFACE

Recent advances in the arts make it possible to illustrate books at much less cost than formerly. An important invention is the process of printing in three colors from half-tone plates. The author of this manual was one of the first to use this process in illustrating a work upon the lepidoptera. When “The Butterfly Book” appeared he received letters from many scientific friends expressing their wonder. Among those who wrote to him was Dr. Samuel Hubbard Scudder, the Nestor among American lepidopterists, who has since passed away. He said: “I am simply astonished at the fidelity to nature displayed by the plates in your book, and at the low price at which the new process permits it to be sold.”

That “The Butterfly Book” met a real need is shown by the fact that more than thirty thousand copies have already found purchasers. It is, however, a biggish book. The publishers, Messrs. Doubleday, Page & Co., have asked me to get up a little pocket manual of the butterflies, similar in form to the “Flower Guide,” which has been most cordially received by the public. I have therefore prepared the following pages, to which in the gracious phrase of our forefathers I now “invite the attention of the gentle reader.”

There are more than six hundred species of butterflies found in North America, north of the Gulf of Mexico and the Rio Grande. Most of these are figured in “The Butterfly Book.” In this manual two hundred and fifty-five species and varieties are depicted in their natural colors. They are mainly the commoner forms, which occur in the more densely inhabited parts of the United States and Canada. I have, however, included numerous forms from the Southern States, and not a few of the more showy species from the Pacific Coast.

In some cases only half of the insect is shown. “Half a loaf is better than no bread.” In some cases only one side of the wings is delineated. Usually this is sufficient for identification. The inhabitants of this earth have never seen but one side of the moon, but they know it when they see it, unless they be like the tipsy pair, one of whom said to the other, who was leaning against a lamp post, “Friend, is that the moon, or a lamp?” and who received the reply: “Don’t ask me, I’m a stranger myself in these parts.” By showing only one half, or one side, of a species I have been able to illustrate many more than I could otherwise have done.

The figures of some of the larger species have been slightly reduced to accommodate them to the page, but as the natural size is always given in the description the student need not be perplexed.

The author hopes that his readers will have as much pleasure in studying the winged fairies of the woods and the fields as he has had in preparing this small pocket guide for their assistance.

INTRODUCTORY

THE PLACE OF BUTTERFLIES IN THE ANIMAL KINGDOM

The Animal Kingdom is divided into various _subkingdoms_. One of these is the subkingdom of the _Arthropoda_. This word is derived from the Greek nouns ἄρθρον (_arthron_) meaning _joint_, and πούς (_pous_) meaning _foot_. The _Arthropoda_ are animals the bodies of which are made up of a series of rings or segments jointed together, and the other organs of which are likewise composed of tubular bodies similarly united. All arthropods are _invertebrates_; that is to say, they do not have backbones and internal skeletons, such as are possessed by fishes, reptiles, birds, and mammals, including man. Vertebrate animals have _endoskeletons_, “inside skeletons.” In a ham, for instance, the bone is internal to the muscular parts, or meat, and lies near the middle. The muscles of a man clothe his bones. In the arthropods, on the contrary, the hard parts clothe the muscles. Arthropods are therefore said to have _exoskeletons_, “outside skeletons.” The body, the legs, and other organs of an insect or a crab consist of a series of hollow tubes held together by flexible skin at the points of union, and controlled in their movements by muscles which pull from the inside. The meat of a lobster is inside of the shell, or exoskeleton, as everybody who has eaten a lobster knows. The arrangement is exactly the reverse of that which we find in the vertebrates.

EXPLANATION OF PLATE A

Fig. a. _Magnified scales of butterflies._ 1, ordinary scale of
_Papilio_; 2, do. of _Colias_; 3 _androconium_, or scale from wing of
male _Neonympha eurytus_; 4, do. of male _Pieris oleracea_; 5, do. of
male _Lycæna pseudargiolus_ (Figs. 1-2 after Verity; Figs. 3-5 after
Scudder).

Fig. b. Patch of scales on wing of _Pieris napi_ (after Verity).

Fig. c. Body of _Anosia plexippus_.

I. Head. 1, antenna; 2, eye; 3, proboscis; 4, palpus; cl.
clypeus; o, occiput.

II. Thorax. 5, prothoracic leg; 6, mesothoracic leg; 7,
metathoracic leg; e, e, e, episterna; c, c, c, coxæ; tr.,
tr., trochanters of last two legs; f, f, femora of do.; s,
s, s, scuta of first, second, and third segments of thorax.

III. Abdomen. 1-9 segments; sp., sp., spiracles (after
Burgess).

Fig. d. Head and legs of _Œneis semidea_, showing aborted front leg.

Fig. e. Palpus of _Argynnis aphrodite_.

Fig. f. Leg of _Argynnis idalia_. 1, coxa; 2, trochanter; 3, femur;
4, tibia; 5, tarsus.

Fig. g. Knobbed antenna of _Argynnis idalia_.

Fig. h. Clubbed antenna of _Basilarchia astyanax_.

Fig. i. Hooked antenna of _Amblyscirtes vialis_.

The subkingdom of the _Arthropoda_ is divided into six _classes_, one of which consists of the _Insecta_ (insects). It is estimated that there are three and a half millions of species of insects upon the globe, not to speak of the vast number of species which are now extinct, and known only by their fossil remains.

The Class _Insecta_ is subdivided into many _Orders_. To attempt even to briefly speak of all these orders would take more space than the publisher has allotted to the author, and it is enough to say that butterflies belong to the order _Lepidoptera_. The lepidoptera are divided into two _Suborders_: the _Rhopalocera_, or Butterflies, and the _Heterocera_, or Moths. Both are characterized by having scaly wings, hence the name, which is derived from the Greek words λεπὶς (_lepis_) meaning _scale_, and πτερὸν (_pteron_) meaning _wing_. Lepidoptera are “scale-winged insects.” Any one who has ever handled a butterfly or moth, must have noticed upon his fingers a dust-like substance, rubbed off from the wings of the captured insect. Upon examining this substance under a microscope it is seen to be composed of minute scales (see Plate A, Fig. _a_), and upon looking at the wing of a butterfly under a magnifying glass it is seen to be covered with such scales, arranged somewhat as the scales upon the sides of a fish, or as the shingles upon the roof of a house (see Plate A, Fig. _b_).

Butterflies are mainly diurnal in their habits, preferring the sunshine. Moths on the other hand are nocturnal, and fly in the dusk, or after dark. Butterflies are therefore often called _diurnal lepidoptera_, and moths are spoken of as _nocturnal lepidoptera_. There are, however, a few butterflies which fly at dusk, and there are many moths which are diurnal in their habits. Such moths are generally gay in color, and for the most part inhabit tropical countries, although we have a few such species in the United States. Ordinarily the best way to distinguish between butterflies and moths is by examining their antennæ, or “feelers,” as they are sometimes incorrectly called. In the case of butterflies the antennæ are thread-like, terminating in a small _knob-like_, or _club-like_ enlargement. It is this fact which has led naturalists to call them _Rhopalocera_. The word is derived from the Greek nouns ῥώπαλον (_rhopalon_) meaning a _club_, and κέρας (_keras_) a _horn_. _Butterflies are lepidoptera having at the end of their antennæ clubs, which are sometimes short, long, or hooked_ (see Plate A, Figs. _g_, _h_, _i_.) The forms assumed by the antennæ of moths are very various. The moths are therefore known as _Heterocera_, the word being compounded from the Greek adjective ἕτερος (_all sorts_) and the noun κέρας (_keras_) a _horn_. _Moths are lepidoptera having all sorts of antennæ, except such as are club-shaped at their ends._ However there is no rule without its exceptions, and there are a few rare moths in tropical lands which have club-shaped antennæ like butterflies, but none of these occur in the region with which this book deals.

THE ANATOMY OF BUTTERFLIES

The body of a butterfly consists of the head, the thorax, and the abdomen (see Plate A, Fig. _c_).

The head carries two relatively large eyes, one on either side. The eyes of insects are compound, and if examined under a microscope are seen to have a multitude of minute facets, which serve to gather the light from all directions, so that butterflies can look forward and backward, upward and downward, as well as outward, all at one time. Between the eyes on the upper part of the head arise the antennæ, of which we have already spoken. The precise function of these organs in insects has been the subject of much discussion. Supposed by some to be ears, by others to be the seat of the sense of smell, by others to combine within themselves these two senses, and by still others to represent a sense which is not possessed by vertebrate animals, their use in the life of insects is not yet clearly understood. The weight of evidence seems to be in favor of the view that they are organs of smell, and it is now quite firmly established by experiment that the organs of hearing in insects are represented by certain pores and openings on their legs. In front between the eyes and below the antennæ are two little organs, each composed of three joints, which are known as the _labial palpi_ (see Plate A, Fig. _e_). Between these, coiled up like a watch-spring, is the proboscis, with which the butterfly sucks up the nectar from flowers or drinks water from moist places (see Plate A, Figs. _c_ and _d_). We have not the space in this little manual to go more deeply into the anatomy of these organs, but enough has been said to enable the beginner to recognize the various parts. The student realizes that the head in general supports the principal organs of sense and the proboscis, or mouth.

The thorax carries the organs of locomotion, which consist of four wings and six feet. The thorax is made up of three segments, or rings, the foremost of which is called the _prothorax_, the next the _mesothorax_, and the hindmost the _metathorax_. The subdivisions of the thorax are not easily distinguishable by examining the body of a butterfly even under a microscope, because the bodies of butterflies are generally heavily clothed with hairs and scales. In order to clearly make out the subdivisions, which we are considering, it is necessary to take a specimen and denude it of its scales and hairs, and even dissect it under a glass. The correctness of the foregoing statements then becomes apparent.

The legs of butterflies are arranged in three pairs, the foremost of which are known as _prothoracic_, being attached to the prothorax; the second pair are called _mesothoracic_, springing, as they do, from the middle segment of the thorax; and the last are styled _metathoracic_ legs, rising from the hindmost segment of the chest (see Plate A, Fig. _c_). It should be noted here that in the great family of the _Nymphalidæ_, or “Brush-footed Butterflies,” in both sexes the anterior, or prothoracic pair of legs, are not fully developed, being aborted (see Plate A, Fig. _d_) and therefore do not serve for walking; and that in the families of the _Erycinidæ_, or “Metal-marks,” and the _Lycænidæ_, or “Blues and Coppers,” the females have six legs adapted to walking, while the males possess only four ambulatory legs, the front pair being in the latter sex aborted in these families, as in the _Nymphalidæ_. The legs of butterflies, like those of all other insects, consist of five parts (see Plate A, Fig. _f_) the first of which, nearest the body, is called the _coxa_, with which articulates a small ring-like piece, known as the _trochanter_. To the trochanter is attached the _femur_, and united with the latter, forming an angle with it, is the _tibia_. The last division of the leg is the _tarsus_, or foot, composed of a series of joints, to the last of which is attached a pair of claws, which in butterflies are generally rather minute, though in other orders of insects these claws are sometimes long and powerful, this being especially true of some beetles. The prothoracic legs of the _Nymphalidæ_ and of the males of the _Erycinidæ_ and _Lycænidæ_ have lost the use of the tarsus, only retaining it in feeble form, and the tibia has undergone modification. In many of the _Nymphalidæ_ the tibia is densely clothed with long hairs, giving this part of the leg the appearance of a brush, whence the name “Brush-footed Butterflies” (see Plate A, Fig. _d_). The tibiæ are often armed with more or less strongly developed spines.

The most striking parts of butterflies are their wings, which in proportion to the size of their bodies are usually very large, and which are remarkable for the beauty of the colors and the markings which they display both on the upper and on the under side.

The wings consist of a framework of horny tubes which are in reality double, the inner tube being filled with air, the outer tube with blood. The blood of insects is not, like that of vertebrates, red in color. It is almost colorless, or at most slightly stained with yellow. The circulation of the blood in the outer wall of the wing-tubes takes place most freely during the brief period in which the insect is expanding its wings after emergence from the chrysalis, concerning which we shall have more to say elsewhere. After the wings of the butterfly have become fully expanded, the circulation of the blood in the wings ceases almost entirely. The horny tubes, which compose the framework of the wings of butterflies, support between them a delicate membrane, to which upon both the upper and lower sides are attached the scales. The two fore wings are more or less triangular in outline; the hind wings are also subtriangular, but are generally more or less rounded on the outer margin, and in numerous forms are provided with tails or tail-like prolongations.

Inasmuch as in describing butterflies authors generally devote a good deal of attention to the markings of the wings, it is important for the student to become acquainted with the terms employed in designating the different parts of the wings (see Plate B, Fig. 10). That part of the wing which is nearest to the thorax, is called the _base_; the middle third of the wing is known as the _median_ or _discal area_; the outer third as the _external_ or _limbal area_. The anterior margin of the wing is called the _costal margin_; the outer edge is styled the _external margin_; the inner edge is known as the _inner margin_. The tip of the front wing is called the _apex_, which may be rounded, acute, falcate (sickle-shaped), or square (see Plate B, Figs. 1-4). The angle formed by the outer margin of the front wing with the inner margin is commonly known as the _outer angle_. The corresponding angle on the hind wing is known as the _anal angle_, and the point of the hind wing, which corresponds with the tip or apex of the fore wing, is designated as the _external angle_. The margins of wings may have different styles of outline, and are spoken of as entire, crenulate, scalloped, waved, lobed, or tailed (see Plate B, Figs. 5-8).

A knowledge of the veins which form the framework of the wings is important, because authors have frequently established genera upon the basis of the wing structure. It is desirable on this account to understand the nomenclature which has been applied to the veins. This nomenclature is somewhat variant, different writers having employed different terms to designate the same vein. In what follows the writer has adopted the designations which are most current, and which are generally accepted by authors. The best understanding of this matter is to be derived from the attentive study of the diagrams given on Plate B, Figs. 9 and 10. The veins in both the fore and hind wings of butterflies may be divided into simple and compound veins. In the fore wing the simple veins are the _costal_, the _radials_, the _submedian_, and the _internal_; in the hind wing they are the _costal_, the _subcostal_, the _radials_, the _submedian_, and the _internal_. The costal vein in the hind wing is, however, generally provided near the base with a short ascending branch, which is known as the _precostal_ vein. In addition to the simple veins there are in the fore wing two branching veins, one immediately following the costal, known as the _subcostal_, and the other preceding the submedian, known as the _median_. The branches of these compound veins are known as _nervules_. The median vein always has three nervules. The nervules of the subcostal veins branch upwardly and outwardly toward the costal margin and the apex of the fore wing. There are always from four to five _subcostal nervules_, variously arranged. In the hind wing the subcostal is simple. The median vein in the hind wing has three nervules, as in the fore wing. In both wings between the subcostal and the median veins toward the base is enclosed the _cell_, which may be either _closed_ or wholly or partially _open_ at its outer extremity. The veinlets which close the cell are known as the discocellular veins, of which there are normally three. From the point of union of these _discocellular veins_ go forth the _radials_, known respectively as _upper_ and _lower_, though the upper radial in many genera is emitted from the lower margin of the subcostal vein.

EXPLANATION OF PLATE B

Fig. 1. _Angulated_ or _acuminate apex_ of fore wing (_Grapta_).

Fig. 2. _Falcate apex_ of fore wing (_Pyrrhanæa_).

Fig. 3. _Square apex_ of fore wing (_Smyrna_).

Fig. 4. _Rounded apex_ of fore wing (_Euptoieta_).

Fig. 5. Hind wing _rounded at outer angle, twice-tailed_ (_Thecla_).

Fig. 6. Hind wing _crenulate, tailed, lobed at anal angle_ (_Papilio_).

Fig. 7. Hind wing with _outer margin entire_ (_Parnassius_).

Fig. 8. Hind wing with _outer margin waved_ (_Argynnis_).

Fig. 9. Neuration of wings of _Anosia plexippus_.

_Veins_: C, costal; SC, subcostal; M, median; SM,
submedian; I, internal; PC, precostal; UDC, upper
discocellular; MDC, middle discocellular; LDC, lower
discocellular; UR, upper radial; LR, lower radial.

_Nervules_: SC 1, 2, 3, 4, 5, first to fifth subcostal
nervules; M 1, 2, 3, first to third median nervules.

Fig. 10. Wing of _Papilio turnus_, showing the names given to the
different parts of the wings of butterflies.

Butterflies generally hold their wings erect when they are at rest, with their upper surfaces facing each other, and only the under surfaces displaying their colors to the eye. In the genus _Ageronia_ the insect prefers, like some moths, to settle upon the bark of trees, with the wings spread flat, and the head pointing downward. Many of the _Hesperiidæ_, or “Skippers,” have the habit when they are at rest of holding the fore wings folded together, while the hind wings are expanded horizontally. Many of the butterflies known as “Hair-streaks,” belonging to the genus _Thecla_ and its allies, have the curious habit, when at rest upon the end of a twig or leaf, of moving their folded wings backward and forward, first on one side and then on the other, thus partially displaying with each movement the splendid blue surfaces of the upper side of the wings.

The abdomen of butterflies consists normally of nine segments (see Plate A, Fig. _c_). In most butterflies except the Ithomiids, the end of the abdomen does not extend beyond the anal angle of the hind wings. In the moths, on the other hand, there are multitudes of genera in which the extremity of the abdomen extends far beyond the hind margin of the posterior wings. This is particularly true of the hawk-moths. A minute examination of the abdomen of a butterfly reveals in each segment except the last a little valve-like orifice on either side. These openings are known as _spiracles_ (see Plate A, Fig. _c_). Through these the insect breathes. Insects do not breathe through their mouths, like vertebrates, and their lungs, or what correspond to the lungs of the higher animals, are not located in the thorax or chest, but in the abdomen. The last segment of the abdomen carries at its extremity the external organs of generation. The male may be distinguished from the female by the so-called _prehensores_, or “claspers,” two flattish, scale-like appendages which adhere one on either side to the last segment of the body. These organs are quite peculiar in their structure, and in recent years have received a great deal of study, as it has been found possible by means of them to distinguish closely allied species, especially among the _Hesperiidæ_. It is, however, not possible within our allotted space to go into a minute discussion of this matter. The abdomen of the female is devoid of these appendages, and in this sex is generally heavier and plumper, especially when the eggs, which fill the ovaries, have not as yet been deposited.

Thus far we have devoted our attention almost exclusively to the consideration of the external organs of the suborder of insects which is under discussion. It may be of interest to devote a few paragraphs to the internal anatomy of butterflies. To do the subject full justice would require a volume; nevertheless some general statements may pave the way for a more studious inquiry on the part of readers.

Butterflies take their nourishment in fluid form, principally from the cups which Flora provides. The organ of ingestion is the proboscis, which communicates with a bulb-like receptacle in the head, known as the pharyngeal sac, controlled by a set of muscles which cause it to alternately expand and contract, very much like the bulb-syringe used by physicians. When the muscles expand a vacuum is created, and the fluid is drawn up from the honeyed chalice of the flower into the receptacle in the head; when they contract, a valve in front closes, a valve behind opens, and the honey in the receptacle is forced backward through the œsophagus into the crop, and thence into the stomach. The stomach lies on the ventral or under side of the body, but above the nervous cord, which lies still more ventrad. The stomach opens posteriorly into the small intestine, which is followed by the colon, the latter in turn being succeeded by the rectum. Connected with the intestines are certain vesicles, which are known as Malpighian vessels, and by some are thought to have the function of the liver in higher animals.

Having thus briefly spoken of the nutritive system we may turn to the circulatory and respiratory systems. The heart of a butterfly, as in all arthropods, lies on the dorsal side of the body. Its location corresponds almost exactly to that occupied in the vertebrate animals by the spinal cord. It is a long tubular organ. It does not possess chambers—ventricles and auricles—such as are discovered in the heart of vertebrates, but it has an enlargement in the mesothoracic region known as the aortal chamber. The movement of the heart is wave-like, analogous to the peristaltic movement in the intestines of the vertebrates. From the heart there go out lateral blood-vessels, which ramify and intermingle with the capillary extremities of the tracheæ, or bronchial tubes, through which air is imported by way of the spiracles, and thus the blood is purified in a manner quite analogous to that in which the blood of the higher vertebrates is purified and freed from waste matter by oxydization. The process is, however, as has already been pointed out, mainly carried on in the abdominal region, and not exclusively in the thorax, as in the case of vertebrates.

The nervous system of butterflies consists of a cord with _ganglia_, or nerve-knots, one for each segment of the body. As there are thirteen segments in the body of a butterfly, there are normally thirteen such ganglia, or nerve centres. The nervous cord lies in a position exactly opposite to that which is held by the spinal cord in vertebrates. It is situated on the ventral side of the body, and more ventrad than all the other internal organs. The ganglion in the head is the largest of all and forms a rudimentary brain, the greater portion of which consists of two relatively large optic nerves.

The internal organs of reproduction in the female consist of the ovaries, from which the eggs pass by way of the oviduct to the ovipositor, which in butterflies is not so conspicuous or remarkable an organ as is the case in many other insects. Communicating with the oviduct are the spermatothecæ, which are receptacles in which is retained the fertilizing fluid received from the male at the time of coition. As the eggs, one by one, are passed from the ovaries into the oviduct, they are impregnated through absorption of the spermatozoa, which enter their walls, imparting to them vitality. The internal organs of the male are tubular vesicles, or testes, which secrete the seminal fluid, which by means of the intromittent organ is introduced into the spermatothecæ of the female. Union between the sexes among insects generally takes place but once, and is not recurrent. The female, having been impregnated, proceeds at once to lay her eggs upon the tender leaves or the bark of the plants upon which her progeny are to be nourished, and then promptly dies. The life of insects in the winged form is usually very brief. Inasmuch as there are great differences between the sexes in insects alike in size, form, color, and markings, it is well for the collector to carefully preserve specimens which may be captured in copulation. Such specimens should be designated as “Taken _in coitu_.” The writer in such cases uses the formula “A ♂ _in coitu_ with B ♀,” which is put in minute handwriting upon a label and placed upon the pin bearing the male insect. Upon the pin carrying the female insect there is put the label “B ♀ _in coitu_ with A ♂.” The finding of insects _in copula_ is sometimes the only way in which to definitely settle the question of sexual relationship between forms. So different are some insects that the two sexes have in a number of cases been described by early writers as belonging not merely to different species, but to different genera, and even families.

THE LIFE HISTORY OF BUTTERFLIES

Almost all insects undergo great changes, or metamorphoses, during their existence. Butterflies furnish no exception to this statement. They exist first as _eggs_; then they appear as _caterpillars_; the third stage is that of the _chrysalis_; the final stage is that of the _imago_, or perfectly developed insect.

THE EGGS OF BUTTERFLIES

The eggs of butterflies are beautiful objects when examined under a glass. They have various forms. Some are spheres or half spheres, some are conical, cylindrical or spindle-shaped, others are flat and resemble little cheeses, and still others have the form of turbans. There is endless variety of form displayed within certain limits. Their surfaces may be quite smooth or they may be adorned with raised ribs and sculpturings (see Plate C, Figs. _f_ and _g_) or marked with little pittings or depressions arranged in geometrical patterns. They vary in color. Some are white, some pale green, or blue-green; others are yellow, orange, red, or purple. They are often spotted and marbled like the eggs of some birds.

The eggs of butterflies are deposited by the female upon the plants which are appropriate to the development of the larvæ. Caterpillars are very rarely promiscuous feeders, and most species are restricted to certain species or genera of plants. Even when they feed upon different plants, observation shows that, having begun to feed upon a certain plant, they prefer this to all others, and do not willingly accept anything else. I have noticed frequently that larvæ which may for instance feed in nature upon the wild plum or the lilac, having begun to feed upon the one will steadily refuse the other if offered to them. On several occasions I have lost broods of caterpillars by attempting to change their diet, though knowing well that the species is found feeding in nature upon the plants which I have offered to them. Almost every plant has a butterfly or moth which is partial to it, and one of the most wonderful things in nature is the way in which the female butterfly, without having received a botanical education, is able to select the plant which will best meet the needs of her progeny, which she never lives to see.

The eggs are deposited sometimes singly, sometimes in small clusters, sometimes in a mass. Fertile eggs, soon after they have been laid, undergo a change in color, and it is then possible with a magnifying glass to see through the thin shell the form of the caterpillar which is being developed within.

When the development is completed the caterpillar emerges either from an opening at the side or at the top of the egg. Many species have eggs provided with a sort of lid, a portion of the shell being separated from the remainder by a thin section, which finally breaks under the pressure of the enlarging embryo within, this portion flying off, the rest adhering to the twig or leaf upon which it has been placed. Many larvæ have the habit, as soon as they have emerged from the egg, of making their first meal upon the shell from which they have just escaped.

CATERPILLARS

The second stage in which the insects we are studying exist is known as the _larval stage_. When it is reached the insect is spoken of as a _larva_, or _caterpillar_ (see Plate C, Fig. _h_). Caterpillars have long, worm-like bodies, which are often thickest about the middle, tapering before and behind, and more or less flattened on the under side. Sometimes caterpillars are oval or slug-shaped. Very frequently their bodies are adorned with hairs, spines, and tubercles of various forms. The body of the larva, like the body of the butterfly, consists normally of thirteen rings or segments, of which the three foremost, just behind the head, correspond to the prothorax, the mesothorax, and the metathorax of the perfect insect, while the remaining nine correspond to the abdomen of the imago. These three anterior segments bear legs, which correspond to the legs of the winged form in their location, and are known as the true legs of the larva. Besides these the caterpillar has about the middle of the body and at its posterior end paired _pro-legs_, as they are called, which are its principal organs of locomotion in this stage, but which do not reappear in the butterfly. The mouth parts of caterpillars are profoundly different from those of the butterfly. The imago lives, as we have seen, upon fluid nourishment, and therefore is provided with a sucking organ, the proboscis. The caterpillar, on the other hand, is armed with a pair of cutting mandibles, with which it shears off tiny strips of the leaves upon which it feeds. It holds the edge of the leaf in place with the three pairs of true legs, while it supports its body upon the pro-legs during the act of eating.

EXPLANATION OF PLATE C

Fig. a. Caterpillar of _Anosia plexippus_ ready to change into a
chrysalis.

Fig. b. Do. after having partly shed its skin.

Fig. c. Do. holding itself suspended in the air by grasping the shed
skin between the edges of the third and fourth abdominal segments, and
feeling about with the cremaster for the button of silk above.

Fig. d. Do. after having caught the button and assumed its final form
as a chrysalis.

Fig. e. Chrysalis of _Papilio philenor_, held by button and girdle of
silk.

Fig. f. Egg of _Basilarchia disippus_, greatly magnified.

Fig. g. Egg of _Anosia plexippus_, greatly magnified.

Fig. h. Caterpillar of _Basilarchia disippus_.

(All the figures are after Riley.)

When the caterpillar emerges from the egg the head is in many cases seen to be very large in proportion to the rest of the body. This relative disparity soon disappears, however, as growth takes place. As the larva increases in size, it soon reaches a point at which the skin in which it made its appearance in the world becomes too small and tight for further comfort and use. Thereupon it proceeds to moult, or shed, this now uncomfortable garment. The skin splits along the back and the caterpillar crawls out of it. Before moulting the caterpillar always takes the precaution to attach this outer skin by strands of silk to the leaf or branch upon which the moult is to take place. Having escaped from the cast-off garment, the caterpillar sometimes turns around and eats it before resuming its vegetable diet. The process of moulting takes place four or five times before the larva changes into a chrysalis.

Caterpillars differ entirely from butterflies in that they are able to produce silk. Silk is a viscous fluid secreted by elongated sacs located in the dorsal region. These sacs communicate with a minute tube-like organ, known as the spinneret, which is located on the under side of the head of the caterpillar, just back of the mandibles. The fluid silk, as it is ejected through the spinneret, immediately hardens on contact with the air and is deposited in the form of very fine threads or filaments which the caterpillar uses for various purposes, sometimes as lines with which to guide itself from place to place and enable it to retrace its steps to its favorite resting-place, sometimes to tie together the leaves in which it forms its nest, or to weave a sort of shelter in which it conceals itself, and finally to make the little buttons and the girdles by which, as we shall see later, the chrysalis is held in place. Many moths weave from silk compact structures known as cocoons, in which the chrysalis is lodged. Butterflies do not weave true cocoons.

The time spent by the insect in the egg is generally short. The time passed in the larval state may be short or long. When butterflies hibernate, or pass the winter, as caterpillars, the time spent in this state is long, and especially in the case of those species which inhabit arctic regions. There are some butterflies which occur north of the Arctic Circle, and we have ascertained that these, because the summers are so short in the far north, pass two summers and the intervening winter in the larval condition, and another winter in the pupal stage, before they emerge and take wing. On the other hand, under more temperate conditions butterflies of certain species may produce two or even three broods in a summer, and in subtropical or tropical lands there may be even more broods produced.

While it is true that almost all the larvæ of lepidoptera subsist upon vegetable food, there are nevertheless exceptions, one of which is that of the Harvester, _Feniseca tarquinius_ (see Plate LXXXVIII, Fig. 1), the slug-like larva of which feeds upon scale-insects, or mealy bugs, sharing the habit with certain allied species which occur in Africa and Asia, as the writer has had occasion to point out a number of years ago in certain of his writings.

THE PUPA, OR CHRYSALIS

The third stage in the life of lepidoptera is known as the pupal stage. The caterpillar, having undergone successive moults and reached maturity, is transformed into a pupa, or chrysalis (see Plate C, Figs. _d_ and _e_). From having been an active, worm-like creature, greedily feeding upon its appropriate food, it reverts to a form which is stationary, as was the egg, and ceases to have the power of locomotion. An examination of the structure of all chrysalids shows that they contain an immature butterfly. The segments of the chrysalids enclose the corresponding segments of the body of the butterfly, and in sheathing plates of chitinous matter are enfolded the wings and all the other organs which are necessary to the life of the butterfly when it shall have emerged and taken wing. The act of transformation from the caterpillar stage to the pupal stage is very wonderful. The caterpillar makes provision for the great change by weaving a little button of silk and, in the case of many of those larvæ, the chrysalids of which are not pendant, by also weaving a little girdle of silk, which it passes around its back, and which holds it in place very much as an Indian baby is held by the strap which passes over the shoulders of the squaw (see Plate C, Fig. _e_). Having made these preliminary arrangements the caterpillar becomes very quiet, its hind pro-legs being securely hooked and tangled into the silken button to which it is attached. After a while, when the proper moment has arrived, the skin of the caterpillar splits, just as in the moults which preceded, and by a series of wriggling or vibratory motions the chrysalis succeeds in working off the skin of the caterpillar until it has all been shed except where near the end of the abdomen the skin is caught between the edges of two of the horny rings which form the abdomen. Then the insect with the _cremaster_, as it is called, a little spikelet at the very tip of the chrysalis, which is armed with small hooks, proceeds to feel about until these hooks become entangled in the silk of the button which has been provided on the under surface of the twig, the stone, or the fence rail, where the transformation is occurring. As soon as the chrysalis is securely hooked into the button of silk it lets go of the little section of the skin by which it has been supported and rapidly assumes the shape in which it will remain until the time of its emergence as a butterfly. These changes are illustrated on Plate C, Figs. _a-d_, which are reproduced from “The Butterfly Book” after the drawings of the late Prof. C. V. Riley. The chrysalids of all the Nymphalidæ are pendant; those of the other families, except the Hesperiidæ, are provided with girdles, as is shown on Plate C, in the figures which represent the chrysalis of _Papilio philenor_. The chrysalids of the Hesperiidæ, like the chrysalids of moths, are either formed in loosely woven coverings of leaves tacked together with silken threads, or lie free under leaves and rubbish upon the ground, thus resembling the chrysalids of moths.

Chrysalids are for the most part rather obscure in coloring, though some are quite brilliantly marked with metallic spots as in the case of the common Milkweed Butterfly, _Anosia plexippus_, the chrysalis of which is pearly green in color, ornamented with bright golden spots.

The forms assumed by chrysalids are very various, especially among the Nymphalidæ, and they are often ornamented with curious projections and tubercles, imparting to them very odd outlines.

Some butterflies remain in the chrysalis stage for only a few days or weeks; others pass the winter in this state, and this is true of many of the species which are found in the colder parts of North America. In temperate regions some butterflies have as many as three broods: the spring brood, which comes forth from chrysalids which have over-wintered, an early summer brood, and a fall brood. In tropical countries many species retain the form of the chrysalis during the dry season, and emerge upon the wing at the beginning of the rainy season, when vegetation is refreshed and new and tender growths take place in the forests.

THE IMAGO, OR WINGED INSECT

We have already spoken at length of the form and structure of butterflies in the preceding paragraphs, which were devoted to the anatomy of butterflies. It remains for us at this point to call attention to the manner in which the butterfly undergoes transformation from the chrysalis. This change is quite as interesting as that which takes place when the caterpillar is transformed into the pupa; and should any of my readers possess chrysalids I would advise them to watch carefully and observe the curious events which follow one another rapidly when the imago comes forth from the cerements of the chrysalis. The coverings which ensheathe the head, the legs, and the antennæ split, the head protrudes, the fore legs are disentangled and are thrown forth, followed almost at once by the other legs, and the insect proceeds to crawl out from the pupal skin, emerging with the wings as miniature objects, the body trailing after as a long worm-like mass. Having liberated itself from the sheathings of the chrysalis, the insect immediately assumes a stationary position, head upward, body hanging downward. Then by the action of the heart the fluids which fill the body begin to be rapidly sent into circulation, more particularly into the wings, which expand second after second, minute after minute, the fluids in the body being transferred through the circulatory system of the wings until the latter, hanging downward, have assumed their full form. The insect then begins gently to move its wings, to fan them, still remaining in the position which it first took. After a while the wings become perfectly dry, and the long worm-like body has shrunk up and has assumed the form which it will retain through the subsequent life of the insect. Madame Butterfly then begins to change her position. She carefully crawls a few steps to try her powers of locomotion. She suddenly expands her wings, and, _presto!_ if you alarm her, she is off, fluttering about the cage in which you may have her, or darting forth into the room and through the open window, hieing herself forth in quest of food, which awaits her in the honeyed cups of the wild flowers.

EXPLANATION OF PLATE D

Fig. 1. Illustration showing the way to disable a butterfly in the net
by gently pinching the body where the wings come together.

Fig. 2. A butterfly net.

Fig. 3. _a_, hoop made of wire, the shanks tied together; _b_,
ferrule, plugged at _c_ with a piece of cork; the shanks having been
put into the top of the ferrule, melted solder is poured into the top,
and a good net-ring is made.

Fig. 4. Piece of paper used to cover cyanide at bottom of jar.

Fig. 5. Collecting jar, with lumps of cyanide and sawdust at bottom,
covered by paper, as shown in Fig. 4.

Fig. 6. Expanding block, used to expand and mount insects, the wings
of which have a tendency to droop or sink down.

Fig. 7. Expanding block, used to mount insects, the wings of which
have a tendency to rise up or close.

COLLECTING BUTTERFLIES

In collecting butterflies the first thing is to get a net of some kind with which to catch the insects without tearing their delicate wings, and thus robbing them of their beauty (see Plate D, Figs. 1 and 2). When I was a boy I made my own nets. I took a stick of tough wood about four feet long, which was to serve as the handle. About seven or eight inches from the upper end I wrapped it with copper wire; fishing line will do as well. Then I split the stick down to the band I had made around it. I then with my knife trimmed the two split portions on their inner sides, so that they might be more flexible. I then fashioned out of a piece of good green hickory (the white outer wood must be used) a bow or hoop about twelve inches wide at its widest part, and fitting this between the split ends of the stick put in a wedge at the bottom of the cleft to keep the split ends well apart and tied it neatly and securely in place. Upon the frame made in this way I put a covering of green mosquito netting in the form of a long bag. Many a fine insect I captured with this simple device, which called only for a good jack-knife, a little ingenuity, ordinary skill in whittling, and a supply of stout string. The cheapest and simplest way to make the frame for a net is to take a long piece of brass, aluminium, or galvanized iron wire about an eighth of an inch in diameter and bend it into a circle, leaving two short shanks at the end. Then fit the shanks into the top of the ferrule of a fishing-rod plugged in the middle with a thin piece of cork or with clay, and pour in melted solder. Plate D, Fig. 3 shows how the “trick” is done.

There are many devices for making frames for folding nets, and there are a number of dealers in the United States who supply such nets at moderate prices. The material for the bag of the net ought to be of light stuff, and I prefer to use tarletan, preferably green in color, or bobbinet. The latter is more durable though somewhat heavier than tarletan. The bag of the net ought to be about three times as long as the diameter of the ring upon which it is placed. It is well, after the net has been sewed upon the ring, to cover it with a band of stout dark-colored muslin, as otherwise the edge of the bag surrounding the ring is apt to become speedily worn and torn.

The collector having provided himself with a net for capturing insects must also provide himself with one or more collecting jars. It is well to have several of these of a size convenient for carrying in the pockets. For large specimens a larger jar is required; for small specimens a smaller receptacle is better. The larger jar should have the mouth about two and one half or three inches in diameter. Wide-mouthed glass phials an inch and a half in diameter serve best for the smaller receptacles. The stopper of the larger jar should be of ground glass, of the smaller jar of good cork. Jelly tumblers or glasses with tin tops make good collecting jars. In preparing the jar for use place a few lumps of cyanide of potash about the size of a filbert at the bottom; then put in a little clean sawdust to keep the pieces of cyanide from rattling about; over the lumps of cyanide paste a sheet of strong white paper perforated with a multitude of holes. In doing this the writer has resorted to a simple method, which is explained in the diagram on Plate D, Fig. 4. A piece of paper is placed under the jar and a circle the size of the inside of the jar is traced upon it. Then a disk is cut out about three quarters of an inch greater in diameter than the original circle. The paper is punctured over the entire surface included within the inner line, and then with scissors little gashes are made from the outer circumference inward, so as to permit of folding the edge of the disk inwardly. A little gum tragacanth, or paste, is then applied to these upturned edges, the disk is then inserted into the jar and pasted securely over the cyanide by means of the upturned flaps. A jar thus charged will last for a long time if kept stoppered when not in use. Cyanide has a tendency to liquefy in the presence of moisture, and it is well therefore to take care to keep the jar closed when not in use. It must, however, be borne in mind that the fumes of hydrocyanic acid (prussic acid), which are active in producing the death of the insect, will not be given off in sufficient volume unless there is a small amount of moisture in the jar, and in very dry climates the writer has sometimes found it necessary to moisten the bottom of the jar with a drop or two of water. Jars also may be charged with lumps of carbonate of ammonia, but as this substance bleaches the wings of insects, especially those which are green in color, its use is not strongly recommended. Figure 5 on Plate D shows a jar prepared for use.

When a butterfly has been caught in the net it is apt to flutter about and struggle violently, thus injuring its wings. It is well therefore as soon as the insect has been captured to take hold of it at the point where the wings join the body, while it is still in the net, and by gently pinching the thorax to disable the insect. The fingers are applied from the outside, as shown in the illustration (see Plate D, Fig. 1). Then the collector, unstoppering his jar, inserts it into the net and allows the butterfly to drop into the jar. Butterflies belonging to the family of the _Hesperiidæ_, or “skippers,” are best captured in the net by holding up the end of the bag. The insects will then fly upward and settle near the top of the bag. The collector puts the open jar with his right hand into the ring of the net and holding the bag with the left hand brings the jar under the butterfly, and then claps his left hand over the mouth of the jar, thus securing the insect in the jar, where after a couple of seconds it will be stunned by the fumes and fall to the bottom. Death is speedy, but not instantaneous, and the insect should be allowed to remain a little while in the jar. Having been asphyxiated by the fumes of the jar, the insect may then be removed and either mounted upon a pin and transferred to a collecting box, which will presently be described, or put into an envelope. It is well not to accumulate too many insects in the collecting jar, as those which are caught later will injure in their struggles those which have been caught first. I make it a rule to rapidly transfer the insects from the collecting jars to the collecting boxes which I carry with me. The preservation of specimens in perfect freshness, without torn or ragged wings, is of the utmost importance, and it is better to take fewer specimens, preserving them in immaculate condition, than to accumulate a quantity of ragged and battered examples. The old adage, “Practice makes perfect,” applies in the use of the net and the poisoning jar. There will necessarily be some failures on the part of the young collector at the outset, but if he is neat and quick of finger he will soon acquire the art of taking and preserving perfect specimens.