Fig. 82.—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.
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. 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 oxy-hydrogen lamp of a sciopticon. In the latter case the compressed air should not have a pressure exceeding fifty 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 containsconcentrated 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 intooperation 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. (See Fig. 83.) A modification of the oven is given in Fig. 84.
Fig. 83.—Drying Oven. A, Lamp; B, pin to hold door open; C, door open; D, glass cover.
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 shrivelled and discolored, and are not nearly as valuable as well-inflated and dried skins.
Fig. 84.—Oven for Drying Larva-skin, made of tin joined without solder and with top made of glass. (After 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 as in Fig. 85. The diverging ends are pressed together, a little shellac is placed upon their tips, and they are then inserted into the opening at the anal extremity of the larval skin. Upon the release ofpressure 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. This method of preparation is applicable to the larvæ of Coleoptera and Diptera as well as to those of the Lepidoptera.
Fig. 85.—Wire Bent into Shape for Mounting Larva. (After Riley.)
An account of the manner of preserving larvæ would not be complete without an account of the manner of rearing them. In rearing the larvæ of Coleoptera, Diptera, and Hymenoptera, the student must be left in a large degree to his own devices. A few large glass jars capable of being closed with a gauze top are necessary, though in the case of the Hymenoptera reliance must be mainly placed upon finding the larvæ in their nests. Bees and wasps construct various larval edifices, and these must be explored as found in nature for a knowledge of the immature insect. Breeding them in captivity is attended by difficulties which are rarely overcome by the most expert, except in a few isolated cases. This is also true, but to a less extent of the larvæ of the Coleoptera. The larvæ of many beetles which are carnivorous may be reared in glass jars, or boxes, covered with fine wire gauze, at the bottom of which earth or sand has been placed, and in which a supply of appropriate food can be put, such as the soft larvæ of beetles, maggots, and bits of meat. It is best to previously scald the earth and sand placed at the bottom of the breeding cages in order to destroy the eggs and small larvæ of other species which might be introduced. The cages should have a sufficient supply of moisture, and, so far as possible, the circumstances should be made to approximate those under which the larvæ were found. The larvæ of wood-boring beetles may be bred in portions of the wood which they frequent. A tight barrel with a cover made of wire gauze fitting closely over the top is a good device. In the fall of the year it may be filled with fallen twigs and pieces of branches from the forest, on which beetles have oviposited, and in the spring there will be generally found a large number of beautiful specimens of species,some of which are otherwise very difficult to secure. The barrels should be placed in a covered spot in the open air, and the twigs and wood occasionally lightly moistened with water. The larvæ of leaf-eating beetles may be bred as the larvæ of lepidoptera. The larvæ of neuropterous insects, such as Myrmeleon, may be easily reared in boxes at the bottom of which sand to the depth of six inches has been placed. They may be fed with house-flies which have been deprived of their wings, and soft bodies of coleopterous larvæ, and the larvæ of ants. The larvæ of the Odonata and aquatic beetles must be reared in aquaria in which there is a muddy bottom provided, and in which there are a few pieces of rotting wood, with loose bark upon it, so that they protrude some inches above the surface of the water, and in which aquatic plants are kept growing. Many aquatic insects pupate under the bark of trees growing at the edge of the water.
Fig. 86.—Breeding Cage. (After Riley.)a, Bottom board;g g, battens to prevent warping;f f, zinc pan four inches deep;d, zinc tube soldered to bottom of pan and intended to hold jar of water for food-plants;e, earth in pan;b, box with glass sides and hinged door;c, removable cap of box covered with wire gauze.
The breeding of the larvæ of lepidopterous insects has received far greater attention than that of other insects, and many modifications of devices for this purpose have been suggested. The simplest devices are often the best, and in the early stages of the smaller forms the best plan is to pot a specimen of the appropriate food-plant, when it is low and herbaceous and capable of being thus treated, and then put it under a cover oftarletan or under a bell glass. When the larva undergoes its transformations in the ground a bed of earth several inches in depth, upon which some dead leaves and litter are placed, should be provided. A convenient form of a breeding-cage is represented in Fig. 86. Mr. W.H. Edwards, who has done more than any other person to elucidate the life-history of North American butterflies, often uses a breeding-cage made of a nail keg, the top of which has been knocked out, and over which gauze netting is tied. The writer has successfully employed, for breeding moths upon a large scale, common store boxes, with about eight inches in depth of good soil at the bottom, covered with a close-fitting frame lid over which mosquito-netting is tacked. Branches of the food-plant are set into the box in jars of water, in which they remain fresh for several days (see Fig. 87). If possible, and if operations are to be prosecuted upon a large scale, it is well to appropriate to breeding purposes a small room from which all the furniture and carpets have been removed. The windows should be closed with gauze netting tacked over them, and the doors should also be made tight so as to prevent the escape of the insects. When the caterpillars descend from the food-plants which are placed in the apartment in jars of water, or in pots, and thus indicate their readiness to undergo transformation, they should be secured and placed in smaller boxes fitted up as before described, and, in case the insect pupates in the soil, provided with a sufficient depth of earth. In case it is desired to go to still greater expense, a small house, arranged after the manner of a greenhouse, and with suitable cages and compartments, may be provided. Such an insect-house exists at Cornell University, and is under the care of that admirable investigator, Professor Comstock, who no doubt would be glad to furnish students with a knowledge of the details of its construction. The larvæ of many lepidopterous insects emerge from the egg in the fallof the year, and after feeding for a time and undergoing one or two moults, hibernate, and upon the return of the springtime begin feeding again, and finally pupate. It is best in the case of such to leave the larvæ in the fall in a cold place, as an icehouse, and to suffer them to remain there until an abundant supply of the proper food-plant can be obtained.
Fig. 87.—Breeding Cage. B, Jar with food-plant; E, box with soil; G, gauze lid.
In the breeding of larvæ experience must be the great instructor, and practice can alone make perfect. No department of entomological study is, however, quite so fascinating as this, even though its prosecution may be somewhat laborious.
Fig. 88.—Net Frame. (After Riley.)a, Wire ring with ends bent to insert in feruleb;c, point where plug and net-handle meet.
Thenameimagois applied by naturalists to the perfect form of insects, which is revealed at the conclusion of the round of metamorphoses. In the collection and the preservation of these the most necessary implement at the outset is thenet. A simple way of making a serviceable and strong net is to take a piece of brass or galvanized iron wire about three feet and six inches in length, and about three-sixteenths of an inch in diameter, and having bent it into the form of a hoop, with the two ends forming shanks, to insert these into the end of a brass ferule such as is used on fishing-rods, and fix them there by pouring in melted lead or solder in such a way that the handle can be inserted into the other end of the ferule. This can be easily accomplished by plugging the handle end of the ferule with a piece of soft wood or with clay. The handle should be light, and not more than four or five feet in length for ordinary use. To the ring of the net a sack made of green tarletan, or less preferably mosquito-netting, about two and a half times as deep as the diameter of the ring, should be sewn. A piece of green muslin should be then stitched on as a binding over the ring. Green is to be always preferred to any other color as less likely to alarm the insects. Nets with folding rings and jointed bamboo handles are to be had of most dealers, and are to be highly recommended for convenience, if well made. In collecting about electric lights which hang high, and along the woodland walks of tropical forests, it is well to be able to addto the length of the handle by inserting more joints of bamboo. Some butterflies are "highfliers." Nets made of stout muslin are useful for sweeping the tops of grass and low herbage, and in this way multitudes of small insects of various orders may be taken. Such nets should be larger than the ordinary net. Nets made of stout lace cloth are used for capturing aquatic insects in pools and ditches. For this purpose a scoop made of wire gauze may also be advantageously employed.
PLATE XXII.Fig. 1.—Beating the Bush.Fig. 2.—A Successful Stroke.
PLATE XXII.Fig. 1.—Beating the Bush.Fig. 2.—A Successful Stroke.
In the capture of insects the umbrella plays, in the hands of a skilful collector, a very important part. It is used as a receptacle for insects which are beaten from the overhanging branches, under which it is held in an inverted position while the operation of beating is going on. As the insects fall they must be caught and placed in the collecting-jars. (See Plate XXII., Fig. 1.)
Fig. 89.—Net-head for Removable Frame. (After Riley.) The frame is made of elastic brass ribbon, and may be put inside of the hat when not in use, and the handle used as a cane.
Fig. 90.—Folding Net. (After Riley.)a, Net-ring open;b, enlarged view of joint and check;c, ring folded and detached from ferule;d, nut sunk into end of ferule;e, screw to hold ring in place;f, illustrating manner of putting ring and rod together.
Collecting-jars are of various sizes. For Lepidoptera the one-pound jars used by Schering for hydrate of chloral, which have nicely ground glass stoppers, are admirable. In preparing the jars the following directions should be closely attended to: Place at the bottom of the jar some lumps of cyanide of potash, over these place a few pieces of paper loosely crumpled and rammed down so asto hold the lumps of the cyanide in position. Pour in two or three drops of water. Take a piece of stout and clean writing-paper and describe upon it a circle of the same size as the inside of the bottle, and around this another circle three-quarters of an inch greater in diameter. Cut out a circular disc of paper, following with the scissors the line of the outer circle. At intervals of a quarter of an inch cut slits all around the disc of paper extending them inwardly only as far as the first circle drawn upon the paper. Fold back the outer edge of the disc upon the side of the paper which is to come uppermost in the bottle. With a pin, or a small punch, pierce a number of holes through the middle of the paper. Apply some gum to the edge of the disc which has been folded back, and fix it securely on the top of the mass of cyanide and paper at the bottom of the jar, by pressing the gummed edge against the sides of the bottle. This method is infinitely preferable to the old way of fixing the cyanide in the bottom of the jar by pouring in a cement of plaster of Paris. Instead of lumps of cyanide of potash, lumps of carbonate of ammonia may be used to charge the poisoning-jar, but a jar so charged must never be used to kill insects which are green in color, as the fumes of the ammonia often serve to bleach these and make them white or brown.
Fig. 91.—Collecting Jar. Cy., Cyanide of potash wedged into place with soft paper; P, perforated paper disc.
In the case of large insects, or insects which struggle violently, a few drops of chloroform may be poured into the collecting-jar, to prevent them from injuring themselves. Chloroform is not, however, to be commended as a killing agent, inasmuch as it induces thoracic spasms, which make the specimen difficult to set after death. In the case of the larger moths and beetles death may be instantaneously induced by injecting a solution of cyanide of potash with a hypodermic syringe. The use of oxalic acid in solution, administered by making an incision into the thorax of the insect with the point of a crow-quill pen dipped into the solution, is not to be highly commended, as the acid changes the color of the specimen, and, after it has been pinned, corrodes the pin. Likewise when specimens have been kept too long in a jar charged with ammonia, and are pinned immediately after they have been taken out, the pins are liable to be corroded and eaten through.
Fig. 92.—Perforated Disc of Paper for Holding Cyanide in Place at Bottom of Jar.
The collector having provided himself with nets and killing-jars, will not be thoroughly equipped for field work until hehasadded to his outfit the necessary conveniences for carrying his captures with him uninjured. The writer, after long experience as a collector in many lands, is inclined to think that the best appliance is a tin box lined with cork, and provided with a compartment in which a cyanide cake[11]may be placed before going to the field, and in which, after the return, when the cyanide cake has been withdrawn, a sponge may be put, which should be saturated with a weak solution of carbolic acid for the double purpose of keeping the specimens from drying out too rapidly and from moulding. The box should not be more than 10 × 8 × 3-1/2 inches inside measurement, and should be divided into two equal parts, hinged at the side which is carried uppermost, and hung over the shoulder by a strap. A pincushion filled with pins may be attached to the belt. A belt arranged like a cartridge-belt, with pockets to carry pillboxes about one and one-half inch square and three-quarters of an inch deep should also be provided. These boxes should have glass bottoms. They are to be used in "boxing" the smaller lepidoptera and other delicate insects which, if killed and pinned on the field, would be too dry upon return from the chase to make good cabinet specimens. Boxed specimens may be kept for a day or two, and killed and mounted at leisure. A bag containing several small boxes may also be carried. These boxes should have in them a supply of paper envelopes, for papering specimens in the way hereafter to be described. A loose sack-coat, with an abundance of capacious pockets inside and out, is indispensable. A small poisoning-jar for beetles should be carried in the right-hand pocket of thepantaloons, a similar jar in the left-hand pocket for hymenoptera and diptera. In the right-hand pocket of the sack-coat should be carried the large jar for killing lepidoptera, and in the left-hand pocket a smaller jar for neuroptera and orthoptera. Thus arrayed the collector is completely furnished for the chase. It will, however, be well for him, if he can, to secure the attendance of an assistant to carry some of his "traps" and assist him. We will now go out with him into the field and give him a few practical instructions as to the best mode of procedure.
First of all, it is proper to observe that it is advisable not to be in a hurry and not to rush over the ground. The representations in comic newspapers of the entomologist, wildly tearing about the fields and in mad haste chasing a butterfly over hills and meadows, are not drawn from a study of the methods of experts. "All things come to him who waits." Slyness, coolness, a keen eye, and adroit quickness in the use of the net are the qualities which yield the largest returns to the collector. In the use of the net the habits of insects must be noted. Those which alight upon the ground or low herbage may be caught by clapping the net over them. Most butterflies and moths have the habit, when caught, of flying upward in the net. Therefore so soon as the insect, if a lepidopteron, is enclosed in the net, hold up the closed end of the sack, and, introducing the poison jar, from which the stopper has been removed, take the insect. A little practice will soon enable the collector to do this without allowing the fly to beat and injure its wings, and without touching them in the least with the fingers. (Plate XXIII., Fig. 1.) A convenient way of securing small insects in the net is by a rapid motion hither and thither, with the mouth open to the wind, to drive them back into the bottom of the sack, and then to place this in the bottle and leave it there a few seconds until the insects are stunned, when they may be shaken into the jar. When the insect alights within reach upon the ends of branches or the tops of flowering plants, it may be swept into the net by a dexterous movement and thus secured. A similar stroke will often, when well aimed, secure specimens flying past the station of the collector. (Plate XXIII., Fig. 2.) Beetles and insects of other orders than the lepidoptera may beplaced in the jars appropriated to them and left there until the return from the fields. With the Lepidoptera it is necessary to exercise greater care. The smaller specimens, such as the Tortricidæ and Phycitidæ and Tineidæ should be "boxed" in the pillboxes provided for this purpose. The Lycænidæ, Hesperidæ, and most of the moths, should be caught in the large jar in the manner just described, and when stunned, pinned and placed in the cork-lined box, where the process of completely depriving them of life will be completed. The larger, and even some of the smaller, butterflies may be killed while in the net by gently pinching them through its folds, between the first finger and the thumb at the point where the wings are attached to the thorax (see Fig. 93). The pressure should be applied when the wings are folded back to back, as the insect sits when in repose. If applied in any other way the specimen is likely to be seriously damaged, and moths should never be thus killed. In pinning specimens in the tin box used for transportation while upon the hunt, the storage power of the box will be increased by pinning a number of specimens upon one pin, thrusting the pin through the insect horizontally and not perpendicularly through the upper surface of the thorax.
Fig. 93.—Method of Pinching a Butterfly.
Fig. 93.—Method of Pinching a Butterfly.
The labors of the collector should not be confined to the day. Multitudes of the rarest and most desirable species are nocturnal in their habits. Some of them are readily attracted to light, though, strangely enough, the individuals among the lepidoptera thus attracted are mainly of the male sex. By placing a lamp at an open window many moths may be secured. Electric lights are good points for the collector, if they are within reach. The burnt and ragged refuse which the cleanerfinds in the globes in the morning, half-buried in the dust of the disintegrated carbons, is of little or no value. Various traps lighted with lanterns have been suggested, but so far few of them have equalled the simple device of a friend of mine, who, living in a tropical country, has set apart a small room for this purpose, and having cleared it of all furniture, and whitewashed the walls, keeps a powerful lamp burning in it every night opposite a large window facing the forest. His captures vary from a dozen to a hundred specimens of lepidoptera every night of the year, and multitudes of insects of other orders. In the temperate zones a favorite method of collecting lepidoptera is by "sugaring." For this a mixture of sugar and stale beer, or molasses and water, flavored with rum, and of about the consistency of thin maple syrup, should be used. It is best applied to the trunks of trees upon the edge of clearings, and on moonlight nights on the side of the wood toward the moon. Apply the mixture to from forty to eighty trees, stumps, or stakes, with a whitewash brush, and then go over the "beat" with a dark lantern and capture the moths in the wide-mouthed cyanide jar. In this way the writer has taken as many as three or four hundred moths in a single evening. The same trees should be sugared and visited night after night, and the best results are often only obtained after a beat has been in operation for some time and the insects have learned to know it. The best catch is generally to be had in the two hours immediately following sunset. In tropical countries, aside from the Erebidæ and allied moths, few species appear to be attracted to sugar, and in warm climates plenty of rum should be added to the mixture. To keep ants off from trees which have been sugared, the writer finds it good to tie a band of dark cloth which has been treated with a saturated solution of corrosive sublimate about the trunk near the ground. This only is to be done where a regular route has been selected for nightly visitation, and it has the disadvantage of keeping away from the baits many beetles which are attracted to sugar. Trees which have been sugared and visited at night should be revisited in the daytime, and many day-flying species will be found feasting upon what has been left by the revellers who attended the banquet of the night before.
PLATE XXIII.Fig. 1.—Bottling a Skipper.Fig. 2.—Japanese Porter with Collecting Boxes.
PLATE XXIII.Fig. 1.—Bottling a Skipper.Fig. 2.—Japanese Porter with Collecting Boxes.
Some insects have quite revolting tastes, and may be capturedby pandering to them. The ordure of wild animals has a charm for many, and by placing the dung of dogs, or civet-cats, or any of the Felidæ, in the woodland paths of tropical forests many great rarities may be secured. Carrion and dead fish in particular are attractive baits.
It has been recently claimed by a writer that painted decoys representing butterflies, placed upon flowers, or kept in motion at the tip of a switch, may be effectively used in securing rare and wild species. The writer has no personal knowledge of the merit of the plan. It might be worth trying, however, in the case of monstrous rarities.
Fig. 94.—Manner of Folding Paper Envelope. A-B, First fold; B-C, second fold; A-D, third fold; B-F, fourth fold; A-E, fifth fold.
Thenext step after the capture of the specimens is to prepare them either for transportation or for the cabinet. If collecting upon a journey, or where facilities for the preparation of specimens for the cabinet are lacking, the insects may be preserved in papers. Common druggists' envelopes are a very convenient resource for the preservation of lepidoptera. They may be purchased by the thousand at about sixty-five cents. If these cannot be had, envelopes may easily be made from pieces of paper, preferably stiff newspaper or common writing-paper upon which ink has not been used. The manner of folding these is illustrated by Figures 94 and 95. Care should be taken to write upon the envelope, before the insect is placed in it, the date and the locality of capture. Beetles, if black and devoid of hairy vestiture, may be preserved in alcohol, and the same course may be taken with many insects of other orders. It is preferable, however, to pack beetles and other hard-bodied insects in layers of cotton batting. A small box may be made to contain an immense number of insects in envelopes or in cotton, and they may thus be safely transported anywhere. In case alcohol is used as a preservative all the specimens of a species should be sorted out and tied together in a small sackmade out of thin netting, and to this should be attached a label giving the date and place of capture and a reference to the note-book. In case cotton layers are employed all the specimens of a species, if numerous, should be placed in one layer, and a memorandum to the same purport as the label inserted.
Fig. 95.—Butterfly in Envelope.
Insects are prepared for the cabinet by being mounted upon pins and "expanded." There are various sorts and sizes of insect-pins, but those made by Klaeger, of Berlin, are generally preferred at the present time by the leading entomologists of the world. The French pins and the so-called "Carlsbader pins" are too long and the points are too fine, and, therefore, too likely to be injured to make them desirable. The English pins are too short, and except in the case of very small insects, are not used by the best collectors. Insects should be mounted high upon the pin,i.e., in such a way that not more than one-fifth or at the most one-fourth of the pin shall be exposed above the body of the specimen. Dr. Staudinger, the celebrated lepidopterist of Germany, makes it his rule to mount all his specimens in such a way that the wings are elevated upon a plane one inch above the tip of the pin. The writer has had the greater part of his collection, of over fifty thousand specimens of lepidoptera, mounted at an average height of seven-eighths of an inch above the points of the pins. The "English method" of mounting low down, and only leaving enough of the pin exposed below to permit of fixing the specimens in the cork at the bottoms of the drawers of the cabinet, is rapidly passing out of vogue, even in England, and is giving place to the "Continental Method." Insect pins are of various sizes; adapted to the size of the insect which they are to carry. The most serviceable sizes and which will be proportioned to the majority of the insects which the collector is likely to take, are Klaeger's No. 3 and No. 5. For very large insects higher numbers may be employed, and for smaller insects lower numbers, though in the case of the latter it is perhaps better to use the short English pins and then to mount the specimens upon the bits of cork or pith which are themselves mounted upon the longer German pins. Such mounts are known as "double mounts" (see Fig. 96). The writer desires to utter a caution against the use of the common black insect-pins so often soldby dealers, and the sole stock in trade of one or two firms of opticians in this country. They are very liable to rust at the point and to bend, and are totally unsuited for use in humid, tropical, and semi-tropical climates, or for collections which are to be transported far over the seas. Beetles should always be pinned through the right elytron. Bugs should be pinned through the scutellum, as the small triangular piece between the elytra is called. All other insects should be pinned in the middle of the thorax, and care should always be taken to set the pins perpendicularly.
Fig. 96.—Double Mount. C, Long pin; P, pith; S, specimen mounted on short pin; L, label.
Fig. 97.—Frame for Mounting Beetles. a, a, Wooden frame; A, B, paper drumhead.
Having pinned the specimen the next step is to expand it properly. In the case of beetles this is done by simply arranging the feet and the antennæ in such a way that they can easily be inspected. In doing this it is well to have a frame seven-eighths of an inch deep, or thereabouts, backed by a thin piece of soft pine, and covered on top by a sheet of paper, which has been first moistened and then pasted around the edges, and which when dry expands like a drumhead. (Fig. 97.) Upon this a number of beetles may be pinned, their feet drawn out, and there be left to dry. In the case of lepidopterous insects, and other insects having considerable expanse of wing, setting-boards are required. These are boards provided with a groove in the middle capable of receiving the body of the insect, and permitting of the expansion of their wings laterally. These boards should be of various widths, so as to be adapted to insects having various expanse of wings, and the grooves also should be of various depths, adapted to insects having bodies of various size. The best form of a setting-board, with which the writer is acquainted, is that given in Fig. 98. The narrow slit below the groove, which is intended for the reception of the body of the insect, admits of passing the pin down to aproper depth, and the depth is regulated of course by the piece at the bottom of the setting-board. The two side pieces should always be from seven-eighths of an inch to an inch thick. The best material is soft, clean pine, or, better still, the wood of the Kiri-no-Ki (Paulownia regalis).
Fig. 98.—Setting-Board.
Fig. 99.—Setting-Board. (After Riley.)
Instead of setting-boards, setting-blocks (see Figs. 100 and 101), may be advantageously employed in setting smaller specimens, especially of the Hesperidæ and the Noctuidæ, the wings of which are refractory, and refuse to be treated in the method that has just been described. Instead of using strips of tracing muslin it is necessary, in the case of setting-blocks, to use threads or cords, which may be adjusted, as is shown in the figure. Care should, however, be taken not to draw the thread or cord so tightly about the wings of the specimens as to cut into their vestiture and thus leave marks.
Fig. 100.—Setting-Block. A, Groove for body of insect; B, nick for holding thread; C, cork to receive point of pin passing through holes in bottom of A.
Fig. 101.—Butterfly Expanded upon Setting-Block.
The insects having been adjusted upon the board, care being taken that the pin is set perpendicularly, the next step is to
Fig. 102.—Setting-Needle.
draw out the wings in the position which they are to maintain when the specimen is thoroughly dry. This is accomplished by means of what are known as "setting-needles" (see Fig. 102). They can easily be made by inserting ordinary needles into handles, which may be made of some soft wood. The writer generally employs as handles for his setting-needles matches, from which the sulphur tip has been removed. In drawing the wings into position care should be taken to plant the setting-needle immediately behind the strong nervure of the costal margin of the wing. Otherwise the wings are likely to be torn and disfigured. The rule in setting lepidoptera is to draw the anterior wings forward in such a way that their posterior margins form a right angle with the axis of the body, which rests in the groove in the middle of the setting-board. The posterior wings are then drawn forward in such a way as fully to expose their outline. The next step is to firmly fix the wings in position, as they have been placed. Some writers recommend for this purpose using short strips of paper over the wings, others recommend placing upon the wings pieces of glass, of a size sufficient to cover the entire wing. A far better plan is to employ strips of tracing muslin, such as is used by draughtsmen and engineers. These strips may be secured at the ends of the setting-board by thumb-tacks, and may be drawn down over the wings of the specimen and securely held by pins in place. Care should be always taken to nicely turn up the edge of the strips nearest to the body, so that a crease or depression may not be left upon the scales covering the wings of the insects when the specimen has been thoroughly dried. The wings having been arranged, the antennæ and the feet may be brought forward and displayed in a natural position. Care should be always taken to lower the antennæ so that they do not stand erect above the head. In the latter position they are very apt to become broken. A number of such boards may be conveniently arranged in a box, as shown in Fig. 103, and if strips of muslin are used, and are firmly held in place by pins, such a box may be transported from place to place, upon the backs of men or beasts, and the process of drying the insects may go onen route, while the naturalist isconducting his investigations. In this manner the writer carried four or five large boxes with him through the interior of Japan (Plate XXIII., Fig. 2), and succeeded in bringing home with him nearly six thousand specimens, dried and ready to place in the cabinet. The length of time which is required for drying, varies of course a little with the temperature, and the amount of humidity in the atmosphere. In some climates it is almost impossible to absolutely dry the specimens, in others they dry very quickly. In the United States a week or ten days will generally suffice to secure that rigidity which is necessary in a cabinet specimen.
Fig. 103.—Box for Receiving Setting-Boards.a, Board partly withdrawn;b,T-shaped strip to hold board in place;c, sliding door of box;d, tongue on edge of door working in groove at front of sides.
The process of drying may be hastened advantageously by placing the setting-boards in a cool oven. The temperature, however, should not be above 130° F. Some insects lose their color when dried, and it is impossible in certain cases to retain them. In some cases also the bodies of insects shrivel up very greatly and become distorted. It is very often advisable in such cases to make an incision into the abdomen and withdraw the viscera and stuff the body with cotton. Spiders should always be treated in this way, and so also the larger Mantidæ and Locustidæ. When the insects have become thoroughly dry, and their wings are rigid, they may be removed from the setting-board, and are now ready for the cabinet. In case, however, it is desired to transport them, as is the case with specimens that have been collected upon a journey, they may be pinned in boxes lined with cork or pith, with their wings "shingled" as in Fig. 104, and they may, if firmly secured to the bottom of the boxes, be in this shape transported for long distances; but it isalways necessary to pack the box in which they are contained in an outer box, separating the inner box from the outer case by at least two inches of straw, excelsior, or some other light and elastic substance, to save the specimens from being jarred in transport.
Fig. 104.—Butterflies Pinned with their Wings Shingled.
Specimens that have been preserved in paper, as described on page 328, in order to fit them for the cabinet, should be relaxed and then expanded. In order to relax them, one of the best methods is to place the envelope which contains the specimen between layers of cloth that have been dampened in pure water, to which has been added a small quantity of carbolic acid, enough to prevent mould. Be careful not to add too much carbolic acid. Another method is to lay the specimens at the bottom of a jar, half-filled with sand, which has been moistened and well carbolized. The jar should be tightly closed, so as to retain the moisture. Specimens that have been fastened with pins may be placed on pieces of board, and then set in a jar, prepared in the way that has been described. After exposure to the moist atmosphere of the jar, or to the moisture contained within the towelling, for a period varying from a few hours to a day, the specimens will be sufficiently relaxed to permit of them being treated as if they had been freshly taken, and mounted and expanded upon the setting-board as described on page 331. It is well to have the top of the jar, before the lid is placed upon it, covered with a layer of blotting-paper, or some other substance which will absorb the moisture which otherwise might drip from the lid upon the specimens below. This is a precaution which is especially necessary in the case of butterflies which are of a bright blue or a pale green color, and which are much disfigured by water stains.
Mould is one of the great enemies of the collector, and strenuous efforts should be made to prevent its appearance in the cabinet or among the specimens. In order to do this, it is well to secure a thorough desiccation of the specimens, but where it isimpossible to thoroughly dry them, moulding may be prevented to a greater or less extent by placing between the paper envelopes pieces of blotting-paper which have been saturated with carbolic acid and permitted to dry. The sides of the boxes containing the specimens may also be painted with carbolic acid. Naphthaline in crystals may be introduced among the envelopes, and this appears in many cases to serve as a partial preventive of mould. When a specimen has been attacked by mould, the mould may be largely removed by thorough drying in a cool oven and then dusting off the specimen with a soft camel's-hair pencil that has been rubbed in carbolic acid and dried.
Specimens sometimes become greasy, and it is then desirable, if possible, to remove the grease with which their bodies and wings are saturated. The only method which can be employed advantageously is that of washing out the grease by means of benzoline, or some of the allied volatile mineral oils.
By immersing a greasy specimen for a considerable time in gasoline, it is possible to remove the grease. The specimen having been thus exposed should be placed in a cool spot, free from dust, and all the gasoline should be allowed to evaporate. Care should be taken to conduct this process away from fire and lights, in order to prevent an explosion. The writer has found that the best method for removing grease is to allow the gasoline to fall drop by drop upon the thorax of the specimen. The specimen is therefore placed in a very large glass jar, say six inches in diameter, and is fixed at the bottom upon a piece of cork, tightly secured in place. The gasoline is placed above and is allowed to filter down from the bottle in which it is contained upon the specimen drop by drop. In this way the grease is gradually washed out, and will be found after a while at the bottom of the jar in the form of thick globules, the density of which causes them to sink to the bottom. In the case of some large bombycid moths the writer has washed out as much as a teaspoonful of animal fat from the body and wings of the specimen, in the manner that has been described.
The receptacles into which entomologists place their collections vary somewhat according to the taste and the length ofthe purse of the collector. Some large collections are contained in boxes, and most of the coleopterists of this country, so far as the writer knows, have adopted these as receptacles for their collections. The boxes should be about two inches deep in the clear, the bottom should be lined with the best quality of cork, about one-fourth of an inch in thickness, and the whole papered inside with white paper. The lid should be fastened upon the lower part of the box, either by a tongue and groove or by thin strips nailed around on the inside and projecting above the margin of the bottom portion at least half an inch. These boxes should also be hinged. The material should be well seasoned. Double boxes with cork on the top and on the bottom are sometimes used, and these may be prepared with backs resembling books, and may be placed upon their ends upon shelves. They should not be laid one upon the other, as the insects pinned upon the upper side are liable sometimes, through jarring, to become detached, and falling out to cause a breakage among the specimens. The writer employs in his own collection drawers twenty-two inches long, eighteen inches wide, and two inches deep, covered with glass, the glass cover being attached to the bottom by a tongue and groove.
The specimens should be kept in the dark, as exposure to light bleaches them, sooner or later. Great pains should be taken to keep out dust, mould, and insect pests, such as Anthrenus and Dermestes. Naphthaline crystals destroy mites and they cannot exist where it is abundantly present. Anthrenus and Dermestes may be kept out of collections by naphthaline, but when they have been once introduced they will remain and propagate in spite of the presence of the drug. In order to exterminate them various agents are employed. The best is perhaps chloroform, and next to this carbon bisulphide. In buying the latter drug, care should be taken to purchase the washed and purified article, which is not as malodorous as the common varieties which used formerly to be sold by druggists. It is, however, highly explosive when mixed in quantity with the air, and care should be taken not to use it in proximity to a light. It has the advantage of destroying at once the imago, the larva, and, perhaps, the eggs of museum-pests. The writermakes it a point annually, in the early summer, to place sufficient chloroform or carbon bichloride in his cabinet drawers to exterminate anything that may be living there, and thus secures comparative immunity from insect attacks.
Instructions as to the use of labels may be restricted to the simple advice to make them small enough to permit of their being placed upon the pins bearing the insects, and to have them written legibly. Of course every label should bear, if it is possible for the student to determine them, the generic and the specific names of the insects, and that of the author of the specific name, together with the date and locality of capture. In writing labels a small crow-quill pen is to be preferred.
A great many instruments of different sorts will suggest themselves to the collector in the process of his labors as being more or less useful, but none will prove more so than the forceps. It is impossible to do good work in the cabinet without a forceps, and those made by Blake, of Philadelphia, are the very best.
Books to be Consulted by the Collector for further Information as to Methods of Manipulating Specimens.
Packard: Guide to the Study of Insects. 8vo. Henry Holt & Co., New York.
Scudder: Butterflies. 8vo. Henry Holt & Co., New York. Kirby and Spence: Introduction to Entomology. Various editions.
McCook: American Spiders. Strecker: American Moths and Butterflies.
A great deal of practical and valuable information is to be derived from the pages of the following journals:
The Canadian Entomologist.
The Bulletin of the Brooklyn Entomological Society. Psyche.
Names of Dealers in Entomological Supplies who are to be Recommended.
John Akhurst, 78 Ashland Place, Brooklyn, N.Y.; pins, etc.
John Burr, North Fifth Street, Camden, N.J.; boxes, cabinets, etc.
Armstrong, Brother & Co., Pittsburgh, Pa.; cork. The largest cork manufacturing firm in the United States. Will cut cork of any size which may be ordered, within practical limits.
Blake & Co., 55 North Seventh Street, Philadelphia; forceps.
The Pests.—If an island of bare rock should be born to-dayin the middle of the Pacific Ocean, and an unpoisoned skin of bird or mammal laid down upon it to-morrow morning, I would wager thatDermestes lardariuswould find that skin before sunset. If you were to prepare a skin without poison, and lock it up immediately in the bowels of a burglar-proof safe, not to be opened for six months, at the end of that time you would find it swarming withDermestes. If you ever omit to poison anything in the shape of a vertebrate specimen, be sure your sin and the beastly bugs will find you out.
Dermestes.—The greatest enemy of the zoological collector and conservator, and one which is world-wide in its distribution, is a small beetle, one-third of an inch in length, commonly called the "bacon beetle." Its flight is rather feeble, but "it gets there just the same." The most common species,Dermestes lardarius, is of a dark, dirty-brown color, with a broad, transverse band of dull gray encircling the middle of the body. The imago is not of much consequence as a destroyer, but the larva, a nasty, hairy, brown-backed, and white-bellied abomination half an inch long, and with an appetite like a hog, is the incarnation of all that is pestiferous. A skull that has been "roughed out" and put away without poisoning will soon be literally swarming withDermesteslarvæ, and half-buried with the brown, powdery excrementation they leave behind. If the curator ever sees a fine, brown dust falling in little heaps outof any part of a mounted specimen, he may know thatDermesteslarvæ are at work.
Not long ago the National Museum was visited by another species of the bacon beetle,Dermestes maculatus, a gray-colored variety, beside which his congener seemed harmless and inoffensive.Maculatuswas an unmitigated terror. He disdained to graze modestly on the outside of a specimen, as didlardarius, but simply began to eat wherever he "lit," and went straight in to a depth of an inch or so, as if shot out of a gun. An unhappy stuffed monkey that once crossed the track of this little fiend had half a dozen neat round holes eaten through the dry skin of his side, and straight on into the hard tow filling for quite an inch. A gimlet could not have done the work half so well. The most ridiculous thing was that this insatiable little monster attacked a plaster cast, and bored it full of holes also! Fortunately for the National Museum, the stay of this highly interesting stranger was of brief duration. He came in 1885, and vanished that same year—so far as my observations went.
Moths.—Next in destructiveness are the tiny moths, of which four species are to be fought in the museum and the household. These are the clothes moth (Tinea flavifrontella), the fur moth (T. pelionella), the carpet moth (T. tapetzella), and the grain moth (T. granella). The perfect moth is of course by preference a night-flying insect, and very seldom flies in the daytime except when disturbed. The imago is harmless, but the larva—a tiny, white worm no thicker than a pin, and about one-tenth of an inch in length—will soon shave the hair off an unpoisoned elk or deer head more smoothly than you could do it with the best razor ever made. Of course moth larvæ are most active and destructive during the breeding season—the warm months from May to October—but in warm rooms they sometimes keep at work all through the winter.
In one sense the moth is the zoologist's most dreaded foe, for the reason that its work is so subtle and unseen. Often the first intimation the victim has of the presence of his enemy is when dusting a favorite head he suddenly knocks off a section of hair half a foot square, exposing underneath the smooth, bare skin covered with fine gray dust. The larvæ of the moth attackbirds and quadrupeds in one way only, that is by eating the roots of the hair or feathers, and the epidermis. Mounted heads of large ruminant animals are the particular prey of these abominable pests, because they cannot be protected by glass cases, and are seldom touched save with a feather duster.
In ethnological collections all the garments of skin and leather, and all the textile fabrics are subject to the attacks of the Tineids, as they also are to those of the species to be noticed next.
Anthrenus.—Although I have seen this "buffalo bug" try hard to make an impression on mounted mammals, I have not yet seen it do harm except to furs and leather or woolen garments. The adult buffalo bug (Anthrenus lepidus) is a tiny, round, brown beetle, with white spots on its elytra, and, as usual, it is the larvæ that do the mischief.
Symptoms of the Presence of Insect Pests.—Whenever little heaps of brown dust are seen accumulating here and there on a pedestal underneath a mounted specimen, know that dermestes are actively at work somewhere above. Sometimes the larvæ will even show themselves on the hair, which means a bad case.
If a perfect moth is seen flying in a case, or resting on a specimen, search at once for the larvæ. The best way to do this is to go over a specimen with a rough brush, or a comb, to see if the hair pulls out at any point. If a tuft of hair gives way at its roots, and you see a bare spot underneath, it means moth larvæ.
Poisoning.—Let us take first the case of a mounted specimen which is known to be infested with the larvæ of eitherDermestesor Tineids. It must be treated thoroughly all over with a powerful poison, not only to kill the insects already there, but to poison any larvæ that may be hatched hereafter and seek to attack it.
If possible, remove the specimen from its pedestal, and beat out of it whatever dust it may contain. Procure a quantity of alcohol sufficient when diluted with fifty per cent of water to completely saturate the hair (or feathers) of the specimen, and dissolve in it some corrosive sublimate—about one ounce to every three pints of the liquid. The point to strive for in making up such a solution is to make it as strong with the corrosive sublimate as it can be without leaving on dark hair a gray (orwhite) deposit when the liquid has evaporated. In practice I always mix the liquid, and then test it with a tuft of black or brown hair. If the deposit left is quite apparent to the eye, a little more alcohol and water must be added. The principle of the process is simply this: The alcohol, being at once very penetrating and very volatile, and also capable of combining chemically with the corrosive sublimate, is used as a vehicle for the distribution of the poison. The poison is carried to the roots of the hair and left there as a deposit when the liquid evaporates. In Chapter XVIII. the method of applying this solution is described. Arsenic water, also described there, isequally good, and any intelligent person can make up either solution and apply it successfully without the slightest difficulty.
When the specimen has dried, the hair must be dressed by brushing and combing it. If the white poison shows on the hair, take a sponge, and with either hot water or alcohol sponge off thesurfaceof the hair, leaving all the unseen poison undisturbed. If your solution contains the proper amount of poison, and is thoroughly applied, I warrant that insects will never again touch that specimen, even though it should exist a thousand years.
It often happens that moths get into cases of birds, or mammals, or insects, which cannot be treated as above without damaging the specimens. In such an event there are several poisons of a volatile character which give off fumes so deadly that no insect can live in them. The best for this purpose is naphthaline crystals, exposed in the cases in little bags made of musquito-netting, used in abundant quantity, and left in the cases, which must of course be kept closed as tightly as possible. In insect collections each box should have a little cone of crystals,[12]as a standing menace to all would-be marauders. Liquid or crystal bisulphide of carbon, exposed in saucers on the bottom of a tightly closed case will also kill whatever living insects may be found therein; but it does not destroy eggs, and by the time it has evaporated another generation of destroyers may have been born, hungrier than the first.
A half-ounce bag of naphthaline crystals will last about three months. Mr. John B. Smith, who published in the "Proceedings of the Entomological Society of Washington," vol. i., No. 2, p. 113, a very interesting paper on "Museum Pests," found in treating some boxes of coleoptera that were infested withTrogodermathat both bisulphide of carbon and naphthaline killed all larvæ and imagoes, and held all the eggs in a dormant condition, even through the summer months, until the poison had all evaporated, when the eggs began to hatch.
At present naphthaline in the form of crystals has become the most popular of the various volatile poisons, and among ornithologists, mammalogists, and entomologists is very generally used. It prevents mould, destroys bacteria and schizomycetes; the salt is perfectly neutral, is not poisonous to man, and is cheap, costing only twenty-five cents per pound.
Poisoning Textile Fabrics and Skin Clothing.—Objects of this class can not be put through any liquid poison, for the reason that some would be made hard and stiff, some would lose their colors, and all would come out in bad shape generally. To meet the exigencies of such cases one alternative is to poison the atmosphere of an air-tight case with some of the volatile poisons already mentioned, and the other is to treat each article with some powerful liquid poison, applied as a fine spray with an ordinary atomizer of gutta-percha, which can be purchased for from one to two dollars. The immense collections of the department of ethnology in the National Museum have necessitated a great amount of poisoning in both these ways, especially the latter, which has the merit of being permanent. In the "Smithsonian Report for 1887," vol. ii., pp. 549-558, Mr. Walter Hough has published a very complete, lucid, and valuable paper on "The Preservation of Museum Specimens from Insects, and the Effects of Dampness," which every zoological conservator should read and hold for ready reference.
In spraying large objects Mr. Hough uses either a Shaw & Geary No. 2 air-compressor (cost, $15) or a four-nozzle gutta-percha atomizer ($2.50), and the spray is from the following solution: