The Butterfly Book Part 3

_How to Get the Eggs of b.u.t.terflies._--The process of breeding may begin with the egg. The skilful eye of the student will detect the eggs of b.u.t.terflies upon the leaves upon which they have been deposited. The twig may be cut and placed in a vase, in water, and kept fresh until the minute caterpillar emerges, and then from time to time it may be transferred to fresh leaves of the same species of plant, and it will continue to make its moults until at last it is transformed into a chrysalis, and in due season the b.u.t.terfly emerges. Eggs may frequently be obtained in considerable numbers by confining the female under gauze, with the appropriate food-plant. A knowledge of the food-plant may often be obtained by watching the female and observing upon what plants she deposits her eggs. The exceedingly beautiful researches of Mr. W.H.

Edwards were largely promoted by his skill in inducing females to oviposit upon their food-plants. He did this generally by confining the female with the food-plant in a barrel or nail-keg, the bottom of which had been knocked out, and over the top of which he tied mosquito-netting.

The plant was placed under the keg. The insects thus confined may be fed with a mixture of honey and water placed upon the leaves.

In collecting caterpillars it is well to have on hand a number of small boxes in which to place them, and also a botany-box in which to bring from the field a supply of their appropriate food.

The process of breeding may begin with the caterpillar. The collector, having discovered the caterpillar feeding upon the branch of a certain plant, provides the creature with a constant supply of the fresh foliage of the same plant, until it finally pupates.

[Ill.u.s.tration FIG. 49.--Cheap form of breeding-cage: _G_, lid covered with mosquito-netting; _E_, pan of earth; _B_, bottle for food-plant.]

_Breeding-Cages._--Various devices for breeding caterpillars and rearing moths and b.u.t.terflies are known. One of the most important of these devices is the breeding-cage, which is sometimes called a vivarium. The simplest form of the vivarium is often the best. In breeding some species the best method is simply to pot a plant of the species upon which the larva is known to feed, and to place the potted plant in a box over which some mosquito-netting is tied. The writer frequently employs for this purpose cylinders of gla.s.s over the top of which perforated cardboard is placed. This method, however, can be resorted to only with the more minute forms and with plants that do not attain great height.

Another form of vivarium is represented in the adjoining woodcut (Fig.

50). The writer has successfully employed, for breeding insects upon a large scale, ordinary store boxes provided with a lid made by fastening together four pieces of wood, making a frame large enough to cover the top of the box, and covering it with gauze. The food-plant is kept fresh in bottles or jars which are set into the boxes. Be careful, however, after you have put the branches upon which the caterpillars are feeding into the jars, to stuff something into the neck of the jar so as to prevent the caterpillar from accidentally getting into the water and drowning himself--a mishap which otherwise might occur. When breeding is undertaken on a still larger scale, it may be well to set apart for this purpose a room, preferably in an outbuilding, all the openings leading from which should be carefully closed so as to prevent the escape of the caterpillars.

[Ill.u.s.tration FIG. 50.--Breeding-cage: _a_, base, battened at _g_ to prevent warping; _b_, removable body of cage, inclosing zinc pan, _f_, _f_, containing jar for plant, _d_, and filled with five inches of soil, _e_; _c_, removable top, covered with wire gauze. The doors and sides are of gla.s.s (Riley).]

_How to Find Caterpillars._--Many species of caterpillars are not hard to discover; they are more or less conspicuous objects, and strike the eye. Some species conceal themselves by weaving together the leaves of the plant on which they feed, or by bending a single leaf into a curved receptacle in which they lie hidden. Others conceal themselves during the daytime about the roots of trees or under bark or stones, only emerging in the night-time to feed upon the foliage. The collector will carefully search for these. The presence of caterpillars is generally indicated by the ravages which they have committed upon the foliage. By carefully scanning a branch the collector will observe that the leaves have been more or less devoured. Generally underneath the tree will be found the fra.s.s, or ejectamenta, of the caterpillar. The presence of the ejectamenta and the evidence of the ravages committed by the larvae upon the foliage will give the collector a clue to the whereabouts of the caterpillar. The writer has found it generally advantageous to search for caterpillars that feed upon trees along the wide, sandy margins of brooks and rivers. The fra.s.s is easily discovered upon the sand, and by casting the eye upward into the foliage it is often easy to detect the insect. The pavements in towns and cities which are bordered by trees may also very well be scanned for evidence of the presence of caterpillars. A favorite collecting-ground of the writer is one of the large cemeteries of the city in which he lives, in which there are numerous trees and a great quant.i.ty of shrubbery. Wood-boring species, as a rule, are more difficult to obtain and rear than those that feed upon the foliage.

_Hibernating Caterpillars._--While some difficulty attends the preservation of chrysalids in the case of those species which pupate in the fall and pa.s.s the winter in the chrysalis state under the ground, far more difficulty attends the preservation of species which hibernate in the caterpillar state. As a rule, it is found best to expose the boxes containing these species in an ice-house or other cold place, keeping them there until there is available an abundant supply of the tender shoots of the plant upon which they are in the habit of feeding.

They may then be brought forth from cold storage and placed in proximity to the food-plant, upon which they will proceed to feed.

THE PRESERVATION OF SPECIMENS

_Papering Specimens._--When time and opportunities do not suffice for the proper preparation of b.u.t.terflies for display in the permanent collection, the collector may, in the case of the larger species, conveniently place them in envelopes, with their wings folded (Fig. 51), and they may then be stored in a box until such time as he is able to relax the specimens and properly mount them. Thousands of insects are thus annually collected. The small drug envelopes, or the larger pay-roll envelopes, which may be bought in boxes by the thousand of any stationer for a comparatively small sum, are preferable because of their convenience. Many collectors, however, paper their specimens in envelopes which they make of oblong bits of paper adapted to the size of the insect. The process of making the envelope and of papering the insect is accurately depicted in the accompanying cut (Fig. 52). The writer finds it good in the case of small b.u.t.terflies to place them in boxes between layers of cheap plush or velvet. A small box, a few inches long, may be provided, and at its bottom a layer of velvet is placed; upon this a number of small b.u.t.terflies are laid. Over them is placed a layer of velvet, with its soft pile facing the same side of the velvet at the bottom. On top of this another piece of velvet is laid, with its pile upward, and other specimens are again deposited, and over this another piece of velvet is laid, and so on. If the box is not filled full at once, it is well to have enough pieces of velvet cut to fill it, or else place cotton on top, so as to keep the layers of velvet from moving or shaking about. A yard or two of plush or velvet will suffice for the packing of a thousand specimens of small b.u.t.terflies.

[Ill.u.s.tration FIG. 51.--b.u.t.terfly in envelope.]

[Ill.u.s.tration FIG. 52.--Method of folding paper for envelopes: first fold on line _AB_; then on _AD_ and _CB_; then on _BF_ and _EA_.]

_Mounting b.u.t.terflies._--When the collector has time enough at his disposal he should at once mount his specimens as they are intended to be displayed in the collection. We shall now proceed to explain the manner in which this is most advantageously accomplished. The insect should first of all be pinned. The pin should be thrust perpendicularly through the thorax, midway between the wings, and at a considerable elevation upon the pin. It should then be placed upon the setting-board or setting-block. Setting-boards or setting-blocks are pieces of wood having a groove on the upper surface of sufficient depth to accommodate the body of the insect and to permit the wings to be brought to the level of the upper surface of the board (Fig. 53). They should also be provided either with a cleft or a hole which will permit the pin to be thrust down below the body of the insect for a considerable distance.

As a rule, the wings of all specimens should be mounted at a uniform elevation of about seven eighths of an inch above the point of the pin.

This is known as the "continental method" of mounting, and is infinitely preferable to the old-fashioned "English method," in which the insect was pinned low down upon the pin, so that its wings touched the surface of the box.

[Ill.u.s.tration FIG. 53.--Setting-board designed by the author. The wings of the insect are held in place by strips of tracing-muslin, such as is used by engineers. The grooves at the side serve to hold the board in place in the drying-box. (See Fig. 59.)]

[Ill.u.s.tration FIG. 54.--Setting-block: _A_, holes to enable the pin to reach to the cork; _C_, cork, filling groove on the bottom of the block; _B_, slit to hold thread.]

[Ill.u.s.tration FIG. 55.--Setting-block with b.u.t.terfly expanded upon it.]

Setting-blocks are most advantageously employed in setting small species, especially the _Hesperiidae_, the wings of which are refractory.

When the insect has been pinned upon the setting-board or setting-block, the next step is to set 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" (Fig. 56). Setting-needles may be easily made by simply sticking ordinary needles into wooden matches from which the tips have been removed. In drawing the wings into position, care should be taken to plant the setting-needle behind the strong nervure on the costal margin of the wing; otherwise the wings are liable to be torn and disfigured. The rule in setting lepidoptera is to draw the anterior wing forward in such a manner that the posterior margin of this wing is at right angles to the axis of the body, the axis of the body being a line drawn through the head to the extremity of the abdomen. The hind wing should then be moved forward, its anterior margin lying under the opposing margin of the front wing. When the wings have thus been adjusted into the position which they are to occupy, slips of tracing-muslin or of paper should be drawn down over them and securely pinned, the setting-needles being removed.

[Ill.u.s.tration FIG. 56.--Setting-needle.]

In pinning down the strips which are to hold the wings in place, be careful to pin around the wing, but never, if possible, through it. When the wings have been adjusted in the position in which they are to remain, the antennae, or feelers, should be attended to and drawn forward on the same plane as the wings and secured in place. This may ordinarily be done by setting pins in such a position as to hold them where they are to stay. Then the body, if it has a tendency to sag down at the end of the abdomen, should be raised. This may also be accomplished by means of pins thrust beneath on either side. The figure on the next page shows more clearly what is intended. When the insect has been set, the board should be put aside in a place where it will not be molested or attacked by pests, and the specimens upon it allowed to dry. A box with shelves in it is often used for this purpose. This box should have a door at the front covered with wire gauze, and the back should also be open, covered with gauze, so as to allow a free circulation of air. A few b.a.l.l.s of naphthaline placed in it will tend to keep away mites and other pests.

The time during which the specimen should remain on the board until it is dried varies with its size and the condition of the atmosphere. Most b.u.t.terflies and moths in dry weather will be sufficiently dried to permit of their removal from the setting-boards in a week; but large, stout-bodied moths may require as much as two weeks, or even more time, before they are dry enough to be taken off the boards. The process of drying may be hastened by placing the boards in an oven, but the temperature of the oven must be quite low. If too much heat is applied, great injury is sure to result. Only a careful and expert operator should resort to the use of the oven, a temperature above 120F. being sure to work mischief.

[Ill.u.s.tration FIG. 57.--Setting-board with moth expanded upon it (Riley).]

[Ill.u.s.tration FIG. 58.--b.u.t.terfly pinned on board, showing method of holding up body and pinning down antennae.]

[Ill.u.s.tration FIG. 59.--Drying-box: _a_, setting-board partly pulled out; _b_, T-shaped strip working in groove on setting-board; _c_, front door, sliding down by tongue, _d_, working in a groove at side in front.]

_Relaxing Specimens._--When b.u.t.terflies or moths have been put up in papers or mounted on pins without having their wings expanded and set it becomes necessary, before setting them, to relax them. This may be accomplished in several ways. If the specimens have been pinned it is best to place them on pieces of sheet-cork on a tray of sand which has been thoroughly moistened and treated with a good dose of carbolic acid.

Over all a bell-gla.s.s is put. A tight tin box will serve the same purpose, but a broad sheet of bibulous paper should always be put over the box, under the lid, before closing it, and in such a way as to leave the edges of the paper projecting around the edges of the lid. This is done to absorb the moisture which might settle by condensation upon the lid and drop upon the specimens. In a bell-gla.s.s the moisture generally trickles down the sides. Earthenware crocks with closely fitting lids are even better than tin boxes, but they must have paper put over them, before closing, in the same way as is done when tin boxes are used. When specimens have been preserved in papers or envelopes these should be opened a little and laid upon damp, carbolized sand under a bell-gla.s.s or in a closed receptacle of some kind. Papered specimens may also be placed in their envelopes between clean towels, which have been moistened in water to which a little carbolic acid has been added. The towels should be wrung out quite dry before using them. The method of placing between towels should never be used in the case of very small and delicate species and those which are blue or green in color. Great care must be exercised not to allow the insects to become soaked or unduly wet. This ruins them. They should, however, be damp enough to allow the wings and other organs to be freely moved. When the insects have been relaxed they may be pinned and expanded on setting-boards like freshly caught specimens. It is well in setting the wings of relaxed specimens, after having thrust the pin through the body, to take a small forceps and, seizing the wings just where they join the body, gently move them so as to open them and make their movement easy before pinning them upon the setting-board. The skilful manipulator in this way quickly ascertains whether they have been sufficiently relaxed to admit of their being readily set. If discovered to be too stiff and liable to break they must be still further relaxed. Dried specimens which have been relaxed and then mounted generally require only a short time to dry again, and need rarely be kept more than twenty-four hours upon the setting-boards.

[Ill.u.s.tration FIG. 60.--Drying-box (Riley).]

The process of setting insects upon setting-blocks is exactly the same as when setting-boards are used, with the simple difference that, instead of pinning strips of paper or tracing-muslin over the wings, the wings are held in place by threads or very narrow tapes, which are wound around the block. When the wings are not covered with a very deep and velvety covering of scales the threads or tapes maybe used alone; but when the wings are thus clothed it becomes necessary to put bits of paper or cardboard over the wings before wrapping with the threads.

Unless this is done the marks of the threads will be left upon the wings. Some little skill, which is easily acquired by practice, is necessary in order to employ setting-blocks to advantage, but in the case of small species and species which have refractory wings they are much to be preferred to the boards.

_The Preparation and Preservation of Eggs._--The eggs of b.u.t.terflies may be preserved by simply putting them into tubes containing alcohol, or they may be placed in vials containing dilute glycerine or a solution of common salt. The vials should be kept tightly corked and should be marked by a label written with a lead-pencil and placed within the bottle, upon which the name of the species and the date of collection should be noted, or a reference made to the collector's note-book.

Unless the eggs of insects are preserved in fluid they are apt in many cases to dry up and become distorted, because, on account of their small size, it is impossible to void them of their contents. The larvae escaping from eggs often void the sh.e.l.l very neatly, leaving, however, a large orifice. Such remnants of sh.e.l.ls may be preserved, as they often are useful in showing some of the details of marking; but great vigilance in securing them should be exercised, for almost all the larvae of b.u.t.terflies have the curious habit of whetting their appet.i.tes for future repasts by turning around and either wholly or partially devouring the sh.e.l.l of the egg which they have quitted. Eggs are most neatly mounted in the form of microscopic slides in glycerine jelly contained in cells of appropriate depth and diameter. It is best, if possible, to mount several specimens upon the same slide, showing the side of the egg as well as the end. A cabinet filled with the eggs of b.u.t.terflies thus mounted is valuable and curious.

_The Preservation of Chrysalids._--Chrysalids may be deprived of their vitality by simply immersing them in alcohol, or they may be killed by means of chloroform, and they may then be fastened upon pins like the imago, and arranged appropriately in the collection with the species.

Some chrysalids, however, lose their color when killed in this way, and it is occasionally well to void them of their contents by making an opening and carefully removing the parts that are contained within, replacing with some material which will prevent the chrysalis from shrinking and shriveling. This method of preserving need, however, be resorted to only in exceptional cases. When a b.u.t.terfly has escaped from its chrysalis it frequently leaves the entire sh.e.l.l behind, with the parts somewhat sundered, yet, nevertheless, furnishing a clear idea of the structure of the chrysalis. If no other specimen of the chrysalis can be obtained than these voided sh.e.l.ls they should be preserved.

_The Preservation of Caterpillars._--The caterpillars of b.u.t.terflies when they first emerge from the egg, and before they make the first moult, are, for the most part, extremely small, and are best preserved as microscopic objects in cells filled with glycerine. After each successive moult the larva increases rapidly in size. These various stages in the development of the caterpillar should all be noted and preserved, and it is customary to put up these collections in vials filled with alcohol or a solution of formaline (which latter, by the by, is preferable to alcohol), or to inflate them. The method of inflation secures the best specimens.

In inflating larvae the first step is carefully to remove the contents of the larval skin. This may be done by making an incision with a stout pin or a needle at the a.n.a.l extremity, and then, between the folds of a soft towel or cloth, pressing out the contents of the abdominal cavity. The pressure should be first applied near the point where the pellicle has been punctured, and should then be carried forward until the region of the head is reached. Care must be exercised to apply only enough pressure to expel the contents of the skin without disturbing the tissues which lie nearest to the epidermis, in which the pigments are located, and not to remove the hairs which are attached to the body.

Pressure sufficient to bruise the skin should never be applied. A little practice soon imparts the required dexterity. The contents of the larval skin having been removed, the next step is to inflate and dry the empty skin. A compact statement of the method of performing this operation is contained in Hornaday's "Taxidermy and Zoological Collecting," from the pen of the writer, and I herewith reproduce it:

+--------------------------------------------------------------+ | EXPLANATION OF PLATE V | | | | Reproduced, with the kind permission of Dr. S.H. Scudder, | | from "The b.u.t.terflies of New England," vol. iii, Plate 84. | | | | CHRYSALIDS IN COLOR AND IN OUTLINE--NYMPHALIDae, LYCaeNIDae, | | PIERINae | | | | | | 1. _Argynnis cybele._ Side view. | | 2. _Argynnis cybele._ Dorsal view | | 3. _Argynnis cybele._ Side view. | | 4. _Argynnis idalia._ Side view. | | 5. _Argynnis aphrodite._ Side view. | | 6. _Argynnis atlantis._ Side view. | | 7. _Melitaea phaeton._ Side view. | | 8. _Euptoieta claudia._ Side view. | | 9. _Euptoieta claudia._ Side view. | | 10. _Brenthis bellona._ Side view. | | 11. _Brenthis bellona._ Side view. | | 12. _Brenthis myrina._ Side view. | | 13. _Brenthis myrina._ Side view. | | 14. _Brenthis myrina._ Dorsal view | | 15. _Melitaea phaeton._ Side view. | | 16. _Melitaea phaeton._ Dorsal view. | | 17. _Melitaea barrisi._ Side view. | | 18. _Melitaea barrisi._ Dorsal view. | | 19. _Phyciodes nycteis._ Side view. | | 20. _Phyciodes tharos._ Dorsal view. | | 21. _Phyciodes tharos._ Side view. | | 22. _Phyciodes tharos._ Side view. | | 23. _Libythea bachmani._ Side view. | | 24. _Libythea bachmani._ Side view. | | 25. _Thecla cala.n.u.s._ Side view. | | 26. _Thecla irus._ Side view, enlarged. | | 27. _Thecla cala.n.u.s._ Side view. | | 28. _Thecla liparops._ Side view. | | 29. _Thecla edwardsi._ Side view. | | 30. _Thecla damon._ Side view. | | 31. _Thecla damon._ Side view, enlarged. | | 32. _Thecla irus._ Dorsal view. | | 33. _Thecla irus._ Side view. | | 34. _Thecla irus._ Side view. | | 35. _Thecla acadica._ Side view. | | 36. _Lycaena pseudargiolus._ Side view. | | 37. _Thecla t.i.tus._ Side view. | | 38. _Thecla niphon._ Side view. | | 39. _Thecla melinus._ Side view. Copied | | from Abbot's drawing in the British | | Museum. | | 40. _Thecla niphon._ Side view. Copied | | from Abbot's drawing in Dr. Boisduval's | | library. | | 41. _Lycaena scudderi._ Side view, enlarged. | | 42. _Lycaena comyntas._ Side view. Copied | | from Abbot's drawing in Dr. Boisduval's | | library. | | 43. _Lycaena pseudargiolus._ Side view, | | enlarged. Copied from Abbot's | | drawing in Dr. Boisduval's library. | | 44. _Lycoena pseudargiolus._ Side view. | | 45. _Feniseca tarquinius._ Side view. | | 46. _Feniseca tarquinius._ Side view. | | Copied from Abbot's drawing in | | the British Museum. | | 47. _Lycaena comyntas._ Side view, enlarged. | | 48. _Lycaena comyntas._ Side view. | | 49. _Chrysopha.n.u.s bypophlaeas._ Side view. | | 50. _Chrysopha.n.u.s thoe._ Side view. | | 51. _Terias nicippe._ Side view. | | 52. _Terias nicippe._ Dorsal view. | | 53. _Colias eurytheme._ Side view. | | 54. _Colias philodice._ Dorsal view. | | 55. _Colias philodice._ Side view. | | 56. _Terias lisa._ Side view. | | 57. _Pieris napi_, var. _oleracea_. Side view. | | 58. _Pieris rapae._ Side view. | | 59. _Euchloe genutia._ Side view. | | 60. _Callidryas eubule._ Side view | | 61. _Callidryas eubule._ Side view. | | 62. _Callidryas eubule._ Dorsal view. | | 63. _Pieris napi_, var. _oleracea_. Side view. | | 64. _Pieris rapae_, var. oleracea. Dorsal view. | | 65. _Pieris rapae._ Dorsal view. | | 66. _Pieris protodice._ Dorsal view. | | 67. _Pieris protodice._ Side view. | | | | [Ill.u.s.tration PLATE V.] | +--------------------------------------------------------------+

[Ill.u.s.tration FIG. 61.--Apparatus for inflating larvae: _B_, foot-bellows; _K_, rubber tube; _C_, flask; _D_, anhydrous sulphuric acid; _E_, overflow-flask; _F_, rubber tube from flask; _G_, standard with c.o.c.k to regulate flow of air; _H_, gla.s.s tube with larva upon it; _I_, copper drying-plate; _J_, spirit-lamp.]

"The simplest method of inflating the skins of larvae after the contents have been withdrawn is to insert a straw or gra.s.s 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 expedients for lessening the labor involved have been devised, some of which are to be highly commended."

[Ill.u.s.tration FIG. 62.--Tip of inflating-tube, with armature for holding larval skin.]

[Ill.u.s.tration FIG. 63.--Drying-oven: _A_, lamp; _B_, pin to hold door open; _C_, door open; _D_, gla.s.s cover.]

"A comparatively inexpensive arrangement for inflating larvae 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 c.o.c.k 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 pa.s.sing 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 c.o.c.k. Upon the tip is fastened a small rubber tube, into the free extremity of which is inserted a fine-pointed gla.s.s 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 larvae is to place them in alcohol. The larvae 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."

[Ill.u.s.tration FIG. 64.--Drying-oven: _a_, sliding door; _b_, lid; _c_, body of oven with gla.s.s 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 sh.e.l.lac is placed upon their tips, and they are then inserted into the opening at the a.n.a.l extremity of the larval skin. Upon the release of pressure they spread apart, and after the sh.e.l.lac 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 OF COLLECTIONS

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.

[Ill.u.s.tration 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.]