Plate V.
Fig. 61.—Apparatus for inflating larvæ: B, foot-bellows; K, rubber tube; C, flask; D, anhydrous sulphuric acid; E, overflow-flask; F, rubber tube from flask; G, standard with cock to regulate flow of air; H, glass tube with larva upon it; I, copper drying-plate; J, spirit-lamp.Fig. 61.—Apparatus for inflating larvæ: B, foot-bellows; K, rubber tube; C, flask; D, anhydrous sulphuric acid; E, overflow-flask; F, rubber tube from flask; G, standard with cock to regulate flow of air; H, glass tube with larva upon it; I, copper drying-plate; J, spirit-lamp.
"The simplest method of inflating the skins of larvæ after the contents have been withdrawn is to insert a straw or grass stem of appropriate thickness into the opening through which the contents have been removed, and then by the breath to inflate the specimen, while holding over the chimney of an Argand lamp, the flame of which must be regulated so as not to scorch or singe it. Care must be taken in the act of inflating not to unduly distend the larval skin, thus producing a distortion, and also to dry it thoroughly. Unless the latter precaution is observed a subsequent shrinking and disfigurement will take place. The process of inflating in the manner just described is somewhat laborious, and while some of the finest specimens which the writer has ever seen were prepared in this primitive manner, various expedientsfor lessening the labor involved have been devised, some of which are to be highly commended.
Fig. 62.—Tip of inflating-tube, with armature for holding larval skin.
Fig. 63.—Drying-oven:A, lamp;B, pin to hold door open;C, door open;D, glass cover.
"A comparatively inexpensive arrangement for inflating larvæ is a modification of that described in the 'Entomologische Nachrichten' (1879, vol. v, p. 7), devised by Mr. Fritz A. Wachtel (Fig. 61). It consists of a foot-bellows such as is used by chemists in the laboratory, or, better still, of a small cylinder such as is used for holding gas in operating the oxyhydrogen lamp of a sciopticon. In the latter case the compressed air should not have a pressure exceeding twenty pounds to the square inch, and the cock regulating the flow from the cylinder should be capable of very fine adjustment. By means of a rubber tube the air is conveyed from the cylinder to a couple of flasks, one of which contains concentrated sulphuric acid, and the other is intended for the reception of any overflow of the hydrated sulphuric acid which may occur. The object of passing the air through sulphuric acid is to rob it, so far as possible, of its moisture. It is then conveyed into a flask, which is heated upon a sand-bath, and thence by a piece of flexible tubing to a tip mounted on a joint allowing vertical and horizontal motion and secured by a standard to the working-table. The flow of air through the tip is regulated by a cock. Upon the tip is fastened a small rubber tube, into the free extremity of which is inserted a fine-pointed glass tube. This is provided with an armature consisting of two steel springs fastened upon opposite sides, and their ends bent at right angles in such a way as to hold the larval skin firmly to the extremity of the tube. The skin having been adjusted upon the fine point of the tube, the bellows is put into operation, and the skin is inflated. A drying apparatus is provided in several ways. A copper plate mounted upon four legs, and heated by an alcohol-lamp placed below, has been advocated by some. A better arrangement, used by the writer, consists of a small oven heated by the flame of an alcohol-lamp or by jets of natural gas, and provided with circular openings of various sizes, into which the larval skin is introduced (Fig. 63).
"A less commendable method of preserving larvæ is to place them in alcohol. The larvæ should be tied up in sacks of light gauze netting, and a label of tough paper, with the date and locality of capture, and the name, if known, written with a lead-pencil, should be attached to each such little sack. Do not use ink on labels to be immersed, but a hard lead-pencil. Alcoholic specimens are liable to become shriveled and discolored, and are not nearly as valuable as well-inflated and dried skins.
Fig. 64.—Drying-oven:a, sliding door;b, lid;c, body of oven with glass sides;d, opening for inserting inflating-tube;e, copper bottom;f, spirit-lamp;g, base (Riley).
"When the skins have been inflated they may be mounted readily by being placed upon wires wrapped with green silk, or upon annealed aluminium wire. The wires are bent and twisted together for a short distance and then made to diverge. The diverging ends are pressed together, a little shellac is placed upon their tips, and they are then inserted into the opening at the analextremity of the larval skin. Upon the release of pressure they spread apart, and after the shellac has dried the skin is firmly held by them. They may then be attached to pins by simply twisting the free end of the wire about the pin, or they may be placed upon artificial imitations of the leaves and twigs of their appropriate food-plants."
THE PRESERVATION AND ARRANGEMENT OFCOLLECTIONS
The secret of preserving collections of lepidoptera in beautiful condition is to exclude light, moisture, and insect pests. Light ultimately bleaches many species, moisture leads to mould and mildew, and insect pests devour the specimens. The main thing is therefore to have the receptacles in which the specimens are placed dark and as nearly as possible hermetically sealed and kept in a dry place. In order to accomplish this, various devices have been resorted to.
Fig. 65.—Detail drawing of front of box, made to resemble a book:s,s, sides, made of two pieces of wood glued together across the grain;t, tongue;g, groove;c, cork;p, paper covering the cork.
Fig. 66.—Detail drawing of front of box:t, top;b, bottom;e, side;f, strip, nailed around inside as atn;c, cork;p, paper lining.
Boxes.—Boxes for the preservation of specimens are made with a tongue on the edges of the bottom fitting into a groove upon the lid, or they may be made with inside pieces fastened around the inner edge of the bottom and projecting so as to catch the lid. The accompanying outlines show the method of joining different forms of boxes (Figs. 65-67). The bottom of the box should be lined with some substance which will enable the specimens to be pinned into it securely. For this purpose sheet-cork about a quarter of an inch thick is to be preferred to all other substances. Ground cork pressed into layers and covered with white paperis manufactured for the purpose of lining boxes. Turf compressed into sheets about half an inch thick and covered with paper is used by many European collectors. Sheets of aloe-pith or of the wood of the yucca, half an inch thick, are used, and the pith of corn-stalks (Indian corn or maize) may also be employed, laid into the box and glued neatly to the bottom. The corn-pith should be cut into pieces about half an inch square and joined together neatly, covering it with thin white paper after the surface has been made quite even and true. Cork is, however, the best material, for, though more expensive than the other things named, it has greater power to hold the pins, and unless these are securely fixed and held in place great damage is sure to result. A loose specimen in a box will work incalculable damage. Boxes should be made of light, thoroughly seasoned wood, and should be very tight. They are sometimes made so that specimens may be pinned both upon the top and the bottom, but this is not to be commended. The depth of the box should be sufficient to admit of the use of the longest insect-pin in use, and a depth between top and bottom of two and a quarter inches is therefore sufficient. Boxes are sometimes made with backs in imitation of books, and a collection arranged in such boxes presents an attractive external appearance. A very good box is made for the United States Department of Agriculture and for the Carnegie Museum in Pittsburgh (Fig. 68). This box is thirteen inches long, nine inches wide, and three inches thick (external measurement). The depth between the bottom and the lid on the inside is two and one eighth inches. The ends and sides are dovetailed; the top and bottom are each made of two pieces of light stuff, about oneeighth of an inch thick, glued together in such a way that the grain of the two pieces crosses at right angles, and all cracking and warping are thus prevented. The lids are secured to the bottoms by brass hooks fitting into eyelets. Such boxes provided with cork do not cost more than fifty-five cents apiece when bought in quantities. Boxes may be made of stout pasteboard about one eighth or three sixteenths of an inch thick, with a rabbet-tongue on the inside. Such boxes are much used in France and England, and when well and substantially made are most excellent. They may be obtained for about thirty-five cents apiece lined with compressed cork.
Fig. 67.—Detail drawing of box, in which the tongue,z, is made of strips of zinc let into a groove and fastened as atn;g, groove to catch tongue;s,s, top and bottom;c, cork.
Fig. 68.—Insect-box for preservation of collections.
Cabinets and Drawers.—Large collections which are intended to be frequently consulted are best preserved in cabinets fitted with glass-covered drawers. A great deal of variety exists in the plans which are adopted for the display of specimens in cabinets. Much depends upon the taste and the financial ability of the collector. Large sums of money may be expended upon cabinets, but the main thing is to secure the specimens from dust, mould, and insect pests. The point to be observed most carefully is so to arrange the drawers that they are, like the boxes, practically air-tight. The writer employs as the standard size for the drawers in his own collection and in the Carnegie Museum a drawer which is twenty-two inches long, sixteen inches wide, and two inches deep (inside measurement). The outside dimensions are: length, twenty-three inches exclusive of face; breadth, seventeen inches; height, two and three eighths inches. The covers are glazed with double-strength glass. They are held upon the bottoms by a rabbet placed inside of the bottom and nearly reaching the lower surface of the glass on the cover when closed. The drawers are lined upon the bottom with cork five sixteenths of an inch thick, and are papered on the bottom and sides with good linen paper, which does not easily become discolored. Each drawer is faced with cherry and has a knob. These drawers are arranged in cabinets built in sections for convenience in handling. The two lower sections each contain thirty drawers, the upper section nine. The drawers are arranged in three perpendicular series and are made interchangeable, so that any drawer will fit into any place in any one of the cabinets. This is very necessary, as it admits of the easy rearrangement of collections. On the sides of each drawer a pocket is cut on the inner surface, which communicates throughan opening in the rabbet with the interior. The paper lining the inside is perforated over this opening with a number of small holes. The pocket is kept filled with naphthaline crystals, the fumes of which pass into the interior and tend to keep away pests. The accompanying figure gives the details of construction (Fig. 69). Such drawers can be made at a cost of about $3.50 apiece, and the cost of a cabinet finished and supplied with them is about $325, made of cherry, finished in imitation of mahogany.
Fig. 69.—Detail drawing of drawer for cabinet:e,e, ends;b, bottom;c, cork;p,p, paper strips in corners of lid to exclude dust;g,g, glass of cover, held in place by top strips,s,s;m,m, side pieces serving as rabbets on inside;po, pocket in ends and sides, sawn out of the wood;x, opening through the rabbet into this pocket;y, holes through the paper lining,p1, allowing fumes of naphthaline to enter interior of drawer;f, front;k, knob;o, lunette cut in edge of the top piece to enable the lid to be raised by inserting the fingers.
Some persons prefer to have the bottoms as well as the tops of the drawers in their cabinets made of glass. In such cases the specimens are pinned upon narrow strips of wood covered with cork, securely fastened across the inside of the drawers. This arrangement enables the under side of specimens to be examined and compared with as much freedom as the upper side, and without removing them from the drawers; but the strips are liable at times to become loosened, and when this happens great havoc is wrought among the specimens if the drawer is moved carelessly. Besides, there is more danger of breakage.
Another way of providing a cheap and very sightly lining for the bottom of an insect-box is illustrated in Fig. 70. A frame of wood like a slate-frame is provided, and on both sides paper is stretched. To stretch the paper it ought to be soaked in water before pasting to the frame; then when it dries it is as tight and smooth as a drum-head.
The beginner who has not a long purse will do well to preserve his collections in boxes such as have been described. They can be obtained quite cheaply and are most excellent. Cabinets are more or less of a luxury for the amateur, and are only a necessity in the case of great collections which are constantly being consulted. The boxes may be arranged upon shelves. Some of the largest and best collections in the world are preserved in boxes, notably those of the United States National Museum.
Fig. 70.—A,A, side and bottom of box;B, frame fitting into box;C, space which must be left between frame and bottom of box;P,P, paper stretched on frame.
Labeling.—Each specimen should have on the pin below the specimen a small label giving the date of capture, if known, and the locality. Below this should be a label of larger size, giving its scientific name, if ascertained, and the sex. Labels should be neat and uniform in size. A good size for labels for large species is about one inch long and five eighths of an inch wide. The labels should be written in a fine but legible hand. Smaller labels may be used for smaller species. A crow-quill pen and India ink are to be preferred in writing labels.
Arrangement of Specimens.—Specimens are best arranged in rows. The males should be pinned in first in the series, after them the females. Varieties should follow the species. After these should be placed any aberrations or monstrosities which the collector may possess. The name of the genus should precede all the species contained in the collection, and after each species the specific name should be placedFig. 71shows the manner of arrangement.
Fig. 71.—Manner of arranging specimens in cabinet.
Insect Pests.—In order to preserve collections, great care must be taken to exclude the various forms of insect pests, which are likely, unless destroyed and kept from attacking the specimens, to ruin them utterly in comparatively a short time. The pests which are most to be feared are beetles belonging to the generaDermestesandAnthrenus. In addition to these beetles, which commit their ravages in the larval stage, moths and mites prey upon collections. Moths are very infrequently, however, found in collections of insects, and in a long experience the writer has known only one or two instances in which any damage was inflicted upon specimens by the larvæ of moths. Mites are much more to be dreaded.
Fig. 72.—Naphthaline cone.
In order to prevent the ravages of insects, all specimens, before putting them away into the boxes or drawers of the cabinet in which they are to be preserved, should be placed in a tight box in which chloroform, or, better, carbon bisulphide, in a small pan is put, and they should be left here for at least twenty-four hours, until it is certain that all life is extinct. Then they should be transferred to the tight boxes or drawers in which they are to be kept. The presence of insect pests in a collection is generally first indicated by fine dust under the specimen, this dust being the excrement of the larva which is committing depredations upon the specimen. In case the presence of the larva is detected, a liberal dose of chloroform should at once be administered to the box or tray in which the specimen is contained. The specimen itself ought to be removed, and may be dipped into benzine. Naphthaline crystals or camphor is generally employed to keep out insect pests from boxes. They are very useful to deter the entrance of pests, but when they have once been introduced into a collection neither naphthaline nor camphor will kill them. Naphthaline is prepared in the form of cones attached to a pin, and these cones may be placed in one corner of the box. They are made by Blake & Co. of Philadelphia, and are in vogue among entomologists. However, a good substitute for the cones may very easily be made by taking the ordinary moth-balls which are sold everywhere. By heating a pin red-hot in the flame of an alcohol-lamp it may be thrust into the moth-ball; as it enters it melts the naphthaline, which immediately afterward cools andholds the pin securely fixed in the moth-ball. In attaching these pins to moth-balls, hold the pin securely in a forceps while heating it in the flame of the lamp, and thrust the red-hot pin into the center of the ball. Naphthaline crystals and camphor may be secured in the corner of the box by tying up a quantity of them in a small piece of netting and pinning the little bag thus made in the corner of the tray. By following these directions insect pests may be kept out of collections. It is proper to observe that while carbon bisulphide is more useful even than chloroform in killing pests, and is also cheaper, it should be used with great care, because when mixed with atmospheric air it is highly explosive, and its use should never take place where there are lamps burning or where there is fire. Besides, its odor is extremely unpleasant, unless it has been washed in mercury.
Greasy Specimens.—Specimens occasionally become greasy. When this happens they may be cleansed by pinning them down on a piece of cork secured to the bottom of a closed vessel, and gently filling it with benzine, refined gasoline, or ether. After leaving them long enough to remove all the grease they may be taken out of the bath and allowed to dry in a place where there is no dust. This operation should not take place near a lighted lamp or a fire.
Mould.—When specimens have become mouldy or mildewed it is best to burn them up if they can be spared. If not, after they have been thoroughly dried remove the mould with a sable or camel's-hair pencil which has been rubbed in carbolic acid (crystals liquefied by heat). Mildew in a cabinet is hard to eradicate, and heat, even to burning, is about the only cure, except the mild use of carbolic acid in the way suggested.
Repairing Specimens.—Torn and ragged specimens are to be preferred to none at all. "The half of a loaf is better than no bread." Until the torn specimen can be replaced by a better, it is always well to retain it in a collection. But it is sometimes possible to repair torn specimens in such a way as to make them more presentable. If an antenna, for instance, has been broken off, it may be replaced neatly, so that only a microscopic examination will disclose the fact that it was once away from the place where it belonged. If a wing has been slit, the rent may be mended so neatly that only a very careful observer can detect the fact. If a piece has been torn out of a wing, it may be replacedby the corresponding portion of the wing of another specimen of the same sex of the same species in such a way as almost to defy detection. The prime requisites for this work are patience, a steady hand, a good eye, a great deal of "gumption," a few setting-needles, a jeweler's forceps, and a little shellac dissolved in alcohol. The shellac used in replacing a missing antenna should be of a thickish consistency; in repairing wings it should be well thinned down with alcohol. In handling broken antennæ it is best to use a fine sable pencil, which may be moistened very lightly by applying it to the tip of the tongue. With this it is possible to pick up a loose antenna and place it wherever it is desired. Apply the shellac to the torn edges of a broken wing with great delicacy of touch and in very small quantity. Avoid putting on the adhesive material in "gobs and slathers." Repairing is a fine art, which is only learned after some patient experimentation, and is only to be practised when absolutely necessary. The habit of some dealers of patching up broken specimens with parts taken from other species is highly to be reprobated. Such specimens are more or less caricatures of the real thing, and no truly scientific man will admit such scarecrows into his collection, except under dire compulsion.
Fig. 73.—Butterflies pinned into a box overlapping one another, or "shingled."
Packing and Forwarding Specimens.—It often becomes necessary to forward specimens from one place to another. If it is intended to ship specimens which have been mounted upon pins they should be securely pinned in a box lined with cork. A great many expanded specimens may be pinned in a box by resorting to the method known as "shingling," which is illustrated in Fig. 73. By causing the wings of specimens to overlap, as is shown in the figure, a great many can be accommodated in a small space. When the specimens have been packed the box should be securely closed, its edges shut with paper, after some drops of chloroform have been poured into the box, and then this box should be placed in an outer box containing excelsior, hay, cotton, or loose shavings in sufficient abundance to prevent the jarring of the inner box and consequent breakage. Where specimens are forwarded in envelopes, having been collected in thefield, and are not pinned, the precaution of surrounding them with packing such as has been described is not necessary, but the box in which they are shipped should always be strong enough to resist breakage. Things forwarded by mail or by express always receive rough treatment, and the writer has lost many fine specimens which have been forwarded to him because the shipper was careless in packing.
Pins.—In the preceding pages frequent reference has been made to insect-pins. These are pins which are made longer and thinner than is the case with ordinary pins, and are therefore adaptable to the special use to which they are put. There are a number of makers whose pins have come into vogue. What are known as Karlsbader and Kläger pins, made in Germany, are the most widely used. They are made of ordinary pin-metal in various sizes. The Karlsbader pins have very fine points, but, owing to the fineness of the points and the softness of the metal, they are very apt to buckle, or turn up at the points. The Kläger pins are not exposed to the same objection, as the points are not quite so fine. The best pins, however, which are now made are those which have recently been introduced by Messrs. Kirby, Beard, & Co. of England. They are made of soft steel, lacquered, possessing very great strength and considerable flexibility. The finest-sized pin of this make has as much strength as the largest pin of the other makes that have been mentioned, and the writer has never known them to buckle at the tip, even when pinned through the hardest insect tissues. While these pins are a little more expensive than others, the writer does not fail to give them an unqualified preference.
Fig. 74.—Butterfly-forceps, half-size.
The Forceps.—An instrument which is almost indispensable to the student of entomology is the forceps. There are many forms of forceps, and it is not necessary to speak at length in reference to the various shapes; but for the use of the student of butterflies the forceps made by the firm of Blake & Co. of Philadelphia is to be preferred to all others. The head of this firm is himself a famous entomologist, and he has given us in the forceps which is illustrated in Fig. 74 an instrument which comes as near perfection as the art of the maker of instruments can produce. The small forceps represented in Fig. 75 is very useful in pinning small specimens. In handling mounted specimens it is well always to take hold of the pin below the specimen with the forceps, and insert it into the cork by the pressure of the forceps. If the attempt is made to pin down a specimen with the naked fingers holding the pin by the head, the finger is apt to slip and the specimen to be ruined.
Fig. 75.—Insect-forceps.
IMMORTALITY
A butterfly basked on a baby's grave,Where a lily had chanced to grow:"Why art thou here with thy gaudy dye,When she of the blue and sparkling eyeMust sleep in the churchyard low?"Then it lightly soared thro' the sunny air,And spoke from its shining track:"I was a worm till I won my wings,And she, whom thou mourn'st, like a seraph sings;Would'st thou call the blest one back?"Sigourney.
A butterfly basked on a baby's grave,Where a lily had chanced to grow:"Why art thou here with thy gaudy dye,When she of the blue and sparkling eyeMust sleep in the churchyard low?"Then it lightly soared thro' the sunny air,And spoke from its shining track:"I was a worm till I won my wings,And she, whom thou mourn'st, like a seraph sings;Would'st thou call the blest one back?"Sigourney.
Sigourney.
"Winged flowers, or flying gems."Moore.
"Winged flowers, or flying gems."Moore.
Moore.
At the base of all truly scientific knowledge lies the principle of order. There have been some who have gone so far as to say that science is merely the orderly arrangement of facts. While such a definition is defective, it is nevertheless true that no real knowledge of any branch of science is attained until its relationship to other branches of human knowledge is learned, and until a classification of the facts of which it treats has been made. When a science treats of things, it is necessary that these things should become the subject of investigation, until at last their relation to one another, and the whole class of things to which they belong, has been discovered. Men who devote themselves to the discovery of the relation of things and to their orderly classification are known as systematists.
The great leader in this work was the immortal Linnæus, the "Father of Natural History," as he has been called. Upon the foundation laid by him in his work entitled "Systema Naturæ," or "The System of Nature," all who have followed after him have labored, and the result has been the rise of the great modern sciences of botany and zoölogy, which treat respectively of the vegetable and animal kingdoms.
The Place of Butterflies in the Animal Kingdom.—The animal kingdom, for purposes of classification, has been subdivided into various groups known as subkingdoms. One of these subkingdoms contains those animals which, being without vertebræ, or an internal skeleton, have an external skeleton, composed of a series of horny rings, attached to which are various organs. This subkingdom is known by naturalists under the name of theArthropoda.The wordArthropodais derived from the Greek language and is compounded of two words, (αρθρον), meaning ajointand (πουσ), meaning afoot. TheArthropodaseem at first sight to be made up of jointed rings and feet; hence the name.
Plate VI.
The subkingdom of theArthropodais again subdivided into six classes. These are the following:
Class I. TheCrustacea(Shrimps, Crabs, Water-fleas, etc.).
Class II. ThePodostomata(King-crabs, Trilobites [fossil], etc.).
Class III. TheMalacopoda(Peripatus, a curious genus of worm-like creatures, found in the tropics, and allied to the Myriapods in some important respects).
Class IV. TheMyriapoda(Centipedes, etc.).
Class V. TheArachnida(Spiders, Mites, etc.).
Class VI. TheInsecta(Insects).
That branch of zoölogy which treats of insects is known as entomology.
TheInsectahave been variously subdivided by different scientific writers, but the following subdivision has much in it to commend it, and will suffice as an outline for the guidance of the advanced student.
Class VI. Insecta (Insects proper)
Heterometabola
For the most part undergoing only a partial metamorphosis in the development from the egg to the imago.
ORDERS
Metabola
Undergoing for the most part a complete metamorphosis from egg, through larva and pupa, to imago.
ORDERS
It will be seen by glancing at the foregoing table that the butterflies and moths are included as suborders in the tenth group of the list, to which is applied the nameLepidoptera. This word, like most other scientific words, is derived from the Greek, and is compounded of the noun (λεπισ), which signifies ascale, and the noun (λεπισ), which signifies awing. The butterflies and moths together constitute the order of scale-winged insects. The appropriateness of this name will no doubt be at once recognized by every reader, who, having perhaps unintentionally rubbed off some of the minute scales which clothe the wings of a butterfly, has taken the trouble to examine them under a microscope, or who has attentively read what has beensaid upon this subject in the first chapter of this book. By referring again to the classification which has been given, it will be noted that the last four orders in the list agree in that the creatures included within them undergo for the most part what is known as a complete metamorphosis; that is to say, they pass through four successive stages of development, existing first as eggs, then as worm-like larvæ, or caterpillars, then as pupæ, and finally as perfect, fully developed insects, gifted for the most part with the power of flight, and capable of reproducing their kind. All of this has been to some extent already elucidated in the first chapter of the present volume, but it may be well to remind the reader of these facts at this point.
Fig. 76.—Antennæ of butterflies.
A question which is frequently asked by those who are not familiar with the subject relates to the manner in which it is possible to distinguish between moths and butterflies. A partial answer can be made in the light of the habits of the two classes of lepidoptera. Butterflies are diurnal in their habits, flying between sunrise and dusk, and very rarely taking the wing at night. This habit is so universal that these insects are frequently called by entomologists "the diurnal lepidoptera," or are simply spoken of as "diurnals." It is, however, true that many species of moths are also diurnal in their habits, though the great majority of them are nocturnal, or crepuscular, that is, flying at the dusk of the evening, or in the twilight of the early morning. Upon the basis of mere habit, then, we are able only to obtain a partial clue to the distinction between the two suborders. A more definite distinction is based upon structure, and specifically upon the structure of the antennæ. Butterflies have long, thread-like antennæ, provided with a swelling at the extremity, giving them a somewhat club-shaped appearance (Fig. 76). This form of antennæ is very unusual among the moths, and only occurs in a few rare genera, found in tropical countries, which seem to represent connecting-links between the butterflies and the moths. All the true moths which are found within the limits of the UnitedStates and Canada have antennæ which are not club-shaped, but are of various other forms. Some moths have thread-like antennæ tapering to a fine point; others have feather-shaped antennæ; others still have antennæ which are prismatic in form, and provided with a little hook, or spur, at the end; and there are many modifications and variations of these forms. The club-shaped form of the antennæ of butterflies has led naturalists to call themRhopalocera, as has been already explained in speaking of this subject on page 17. Moths are calledHeterocera. The wordHeterocerais compounded of the Greek word (ἑτερον), meaningother, and the Greek word (κερασ), meaning ahorn. They are lepidoptera which have antennæ which areother than club-shaped. Besides the distinctions which exist in the matter of the form of the antennæ, there are distinctions in the veins of the wings, and in the manner of carrying them when at rest or in flight, which are quite characteristic of the two groups; but all of these things the attentive student will quickly learn for himself by observation.
Fig. 77.—Antennæ of moths.
Scientific Arrangement.—Having thus cast a passing glance at the differences which exist between moths and butterflies, we take up the question of the subdivision of the butterflies into natural groups. Various systems of arranging butterflies have been suggested from time to time by learned writers, and for a knowledge of these systems the student may consult works which treat of them at length. It is sufficient for beginners, for whom this book is principally written, to observe that in modern science, for purposes of convenience, as well as from regard for essential truth, all individuals are looked upon as belonging to aspecies. A species includes all those individuals, which have a common ancestry, and are so related in form and structure as to be manifestly separable from all other similarly constituted assemblages of individuals. For instance, all the large cats having a tawny skin, and in the male a shaggy mane, constitute a species, which we call the lion; the eagles in the eastern United States,which in adult plumage have a snow-white head and neck and a white tail, constitute a species, which we know as the "white-headed" or "bald-headed" eagle. Species may then be grouped together, and those which are manifestly closely related to one another are regarded as forming a natural assemblage of species, to which we give the name of agenus. For example, all the large cats, such as the lion, the tiger, the puma, and the jaguar, are grouped together by naturalists, and form a genus to which is given the Latin nameFelis, meaningcat. The name of the genus always comes before that of the species. Thus the tiger is spoken of scientifically asFelis tigris. The genera which are closely related to one another may again be assembled assubfamilies; and the subfamilies may be united to formfamilies. For instance, all the various genera of cats form a family, which is known as theFelidæ, or the Cat Family. A group of families constitutes asuborderor anorder. The cats belong to theCarnivora, or order of flesh-eating animals.
In zoölogy family names are formed with the termination-idæ, and subfamily names with the termination-inæ.
Everything just said in regard to the classification of the higher animals applies likewise to butterflies. Let us take as an illustration the common milkweed butterfly. Linnæus for a fanciful reason gave this insect the namePlexippus. This is its specific name, by which it is distinguished from all other butterflies. It belongs to the genusAnosia. The genusAnosiais one of the genera which make up the subfamily of theEuplœinæ. TheEuplœinæbelong to the great family of theNymphalidæ. TheNymphalidæare a part of the suborder of theRhopalocera, or true butterflies, one of the two great subdivisions of the orderLepidoptera, belonging to the great classInsecta, the highest class in the subkingdom of theArthropoda. The matter may be represented in a tabular form, in the reverse order from that which has been given:
Subkingdom,Arthropoda.Class,Insecta.Order,Lepidoptera.Suborder,Rhopalocera.Family,Nymphalidæ.Subfamily,Euplœinæ.Genus,Anosia.Species,Plexippus(Milkweed Butterfly).
Varieties.—A still further subdivision is in some cases recognized as necessary. A species which has a wide range over an extensive territory may vary in different parts of the territory within which it is found. The butterflies of certain common European species are found also in Japan and Corea, but, as a rule, they are much larger in the latter countries than they are in Europe, and in some cases more brightly colored. Naturalists have therefore distinguished the Asiatic from the European form by giving the former what is known as a varietal name. Similar differences occur among butterflies on the continent of North America. The great yellow and black-barred swallowtail butterfly known asPapilio turnusoccurs from Florida to Alaska. But the specimens from Alaska are always much smaller than those from other regions, and have a very dwarfed appearance. This dwarfed form constitutes what is known as a local race, or variety, of the species. The members of a species which occur upon an island frequently differ in marked respects from specimens which occur upon the adjacent mainland. By insulation and the process of through-breeding the creature has come to acquire characteristics which separate it in a marked degree from the closely allied continental form, and yet not sufficiently to justify us in treating it as a distinct species. It represents what is known as an insular race, or variety, and we give it therefore a varietal name. Naturalists also distinguish between seasonal, dimorphic, melanic, and albino forms. Names descriptive or designatory of these forms are frequently applied to them. All of this will become plainer in the course of the study of the succeeding pages, and in the effort to classify specimens which the student will make.
Sex.—The designation of the sex is important in the case of all well-ordered collections of zoölogical specimens. As a measure of convenience, the male is usually indicated by the sign of Mars, ♂, while the female is indicated by the sign of Venus, ♁. The inscription, "Argynnis Diana, ♂," therefore means that the specimen is a male ofArgynnis Diana, and the inscription, "Argynnis Diana, ♁," means that the specimen is a female of the same species. These signs are invariably employed by naturalists to mark the sexes.
The Division of Butterflies into Families.—Without attempting to go deeply into questions of classification at the present point,it will be well for us to note the subdivisions which have been made into the larger groups, known as families, and to show how butterflies belonging to one or the other of these may be distinguished from one another. There are five of these families represented within the territory of which this book takes notice. These five families are the following: