[a]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 a, Board partly withdrawn; b, T-shaped strip to hold board in place; c, sliding door of box; d, tongue on edge of door working in groove at front of sides.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 is always 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.
[a]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 is impossible 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 of the 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 writer makes 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.