As for mould, it is best destroyed by the application of phænic or carbolic acid, mixed with three parts of ether or spirit. As preventives, the specimens should be kyanized as above. Caution in the use of laurel as a killing agent must be exercised, and the collection must be kept in a dry room.
Grease may be removed by soaking the insects in pure rectified naphtha or benzole, even by boiling them in it if necessary. When the bodies only are greasy, they may be broken off, numbered, and treated as above. After the grease is thoroughly softened, the insects should be covered up in powdered pipeclay or French chalk, which may be subsequently removed by means of a small sable brush. As a precaution against grease, it is advisable to remove the contents of the abdomina by slitting up the latter beneath with a finely pointed pair of scissors before they are thoroughly dry, and packing the cavities with cotton wool. The males, especially of such species as have internal feeding larvæ, should be thus treated.
Some prefer to keep their collections in well-made store boxes, which possess many advantages over the cabinet; for example, they may be kept like books in a bookcase, the upright position rendering the contents less liable to the attacks of mites; they are more readily referred to, and are more portable, and they admit of our gradually expanding our collections to any extent. Cabinets, on the other hand, are preferred by many, for the reasons that they are compact and generally form a handsome article of furniture; moreover, good cabinets are made entirely of mahogany, which is the best wood for the purpose; deal, and other woods containing resinous matter, having a decidedly injurious effect on the specimens. As a preservative, there is, after all, perhaps nothing better than camphor; but it should be used sparingly, or its tendency will be to cause greasiness of the specimens.
V.
BEETLES.
By E. C. Rye, F.Z.S., etc.
The general rules, so ably expounded by Dr. Knaggs in his instructions for collecting Lepidoptera, as to constant alertness and making "the reason why" the starting-point of investigation, apply with equal force to the collector of Coleoptera, and need not be here recapitulated. But they do not, in the instance of the latter, require generally to be observed, except as to the perfect state of beetles; for, owing to the hidden earlier conditions of life of most of those insects, and to the long period during which these conditions exist, it is but seldom that the pursuit of rearing them, so universally and profitably adopted by the Lepidopterist, is found of much use to the collector of beetles. And this is very much to be regretted; because, in the majority of cases, if the latter succeed in rearing a beetle from its earliest stage, and keep proper notes of its appearance and habits, he will probably be adding to the general stock of knowledge, as the lives of comparatively few, even of the commonest species, are recorded from the beginning. It may be, also, in addition to the reasons above mentioned, for the usual want of success attending the rearing of beetle larvæ, that the fact of bred specimens being frequently (from the artificial conditions attending their development, and from their not being allowed that length of time which, in a state of nature, they require after their final change before they are ready to take an active part in their last stage of life) not nearly so good as those taken at large, militates considerably against the more general use of this method of adding to a collection. In this respect, of course, the Lepidopterist is actuated by precisely opposite motives; as for him, a bred specimen is immeasurably superior to one captured. And the fact of so few beetle larvæ being known at all, or, if known, only to the possessor of somewhat rare books, renders it very likely that a mere collector, finding a considerable expenditure of patience and trouble result in the rearing of a species of which he could at any time readily procure any number of specimens, may very probably abandon rearing for the future.
These observations, however, are not in the least intended to dissuade anyone from breeding or endeavouring to breed beetles. On the contrary, it is obvious from them that it is precisely by attending to these earlier stages that the earnest student (novice or expert) has the most chance of distinguishing himself, on account of the more open field for discovery. And in the instance of many small, and especially gregarious, beetles, breeding from the larvæ is frequently very easy, if only the substances (fungus, rotten wood, roots, stems of plants, &c.) containing them be carefully left in precisely the state as when found, and be exposed to the same atmospheric or other important conditions. In fact, to ensure success and good specimens, it is best that in their early stages beetles should be "let alone severely."