Of the orders Coleoptera, Orthoptera, and Hemiptera. These are easily preserved.
They are killed by immersing in scalding water, and then laid upon blossom or blotting paper, for the purpose of absorbing as much of the moisture as possible; or they may be placed in a tin box, with a little camphor in it, near the fire, which soon kills them. This is, besides, of considerable effect in their preservation.
Insects of the genera Gryllus (Cricket), Locusta (Locusts), etc., have tender bodies, and are sure to shrivel in drying. The intestines should therefore be extracted, while they are yet moist, and skin filled with cotton, as directed with some of the spiders.
When Coleopterous insects are set with the wings displayed, the elytra should be separated, and the pin passed through their body near the middle of the thorax, as in Fig. 35. The wings are exhibited as in the act of flying, and are retained in this situation until they are quite dry, by the cord braces. The insects of this order should always have the pin passed through the right elytra on the right side, as shown at Fig. 37, that is, it should pass underneath, between the first pair of feet and the intermediate ones.
The legs, palpi and antennae should be displayed in a natural order on the setting board, and retained in the position by means of pins and braces, as shown in Figs. 35, 37. These must be kept in that state, either longer or shorter, according to the insect and the state of the weather, as, if placed in a cabinet before they are quite dry, they are sure to get mouldy, and will ultimately rot.
Minute insects should be attached to cards with gum, as shown, Figs. 34 and 39, with the legs and other organs displayed. Entomologists generally adapt triangular cards as at Fig. 38, as less liable to hide the parts of the insects.
Order Lepidoptera. Mr. Haworth, in mentioning the tenacity of life in the Goat Moth, states that "the usual way of compressing the thorax is not sufficient to kill this insect. They will live several days after the most severe pressure has been given there, to the great uneasiness of any humane entomologists. The methods of suffocation by tobacco or sulphur are equally inefficacious, unless continued for a greater number of hours, than is proper for the preservation of the specimens. Another method now in practice is better, and however fraught with cruelty it may appear to the inexperienced collector, is the greatest piece of comparative mercy that can, in this case, be administered. When the larger Moths must be killed, destroy them at once by the insertion of a strong, red-hot needle into their thickest part, beginning at the front of the thorax. If this be properly done, instead of lingering through several days, they are dead in a moment. It appears to me, however, that insects being animals of cold and sluggish juices, are not so susceptible of the sensations we call pain, as those which enjoy a warmer temperature of body, and a swifter circulation of the fluids. To the philosophic mind it is self-evident that they have not such acute organs of feeling pain as other animals of a similar site, whose juices are endowed with a quicker motion, and possess a constant, regular and genial warmth.
Butterflies are soon killed by passing a pin through the thorax. The pin passed through the thorax of small moths generally proves almost instantly fatal to them.
The best manner of preserving the minute species of moths is by pill-boxes, as above stated, each moth being kept in a separate box. We have found the following the best mode of destroying them:
A piece of flat hard-wood is taken, and a circular groove cut in it, sufficiently deep to admit the mouth of a tumbler being placed within it. In the center of the wood, pierce a hole about a third of an inch in diameter in its center: place the pill box under this tumbler, with the lid off, and the insect will soon creep out; but whether it does so or not, a match well primed with sulphur is lighted and placed into the hole under the center of the tumbler, which will suffocate the insect in a few seconds. I have also found this an effectual method of killing the larger species of butterflies, and moths. In piercing them, the pin should be quite perpendicular, that no part of their minute frame should be hidden by its oblique position.
The larger insects of this order are set by braces chiefly. A single one should in the first place be introduced under the wing, near the thorax, as shown in Fig. 36, and a longer brace extending over the wings. These should not bear upon the wings, but be ready to rest gently on them, when required. The wings are now elevated to their proper position by the setting needle, and other braces are used as necessity dictates. The feet and antennas are extended and kept in their places by means of pins, in which operation small braces are also occasionally used.
The French entomologists set butterflies, moths, and sphinges, on a piece of soft wood, in which they have excavated a groove for the reception of the body, as deep as the insertion of the wings. They are otherwise preserved as above directed.
In the larger butterflies, moths, and sphinges, the abdomen should be perforated, its contents extracted, and then stuffed with fine cotton, after having been washed internally with the solution of corrosive sublimate. Indeed, the cotton should also be rubbed with arsenical soap before being introduced, as these insects are particularly liable to the attack of smaller insects, such as the mite.
Several of the moth tribe are extremely liable to change their color some time after they have been placed in a cabinet. This change is frequently occasioned by an oily matter which is common to many of them. This first makes its appearance in small spots on the body, but soon spreads itself over the abdomen, thorax, and wings; and ends in a total obliteration of all the beautiful markings. A method which has been sometimes successfully adopted is to sprinkle all the wings with powdered chalk, and holding a heated iron over it; the chalk absorbs the grease, and may then be blown off by means of a pair of small bellows. Another way of applying the chalk, and perhaps the better of the two, is to throw some powdered chalk on the face of a heated iron, and then put it into a piece of linen cloth, and apply it to the body of the insect; the heat of the iron will soften the grease, and the chalk will absorb it.
Another method is to hold a heated iron over the insects for a few minutes, and then to wash the spotted or greasy places with ox-gall and water, applied with a camel-hair pencil, and afterwards wash it with pure water, and dry it by an application of blotting paper, and when perfectly dry imbue it with the solution of corrosive sublimate. But grease seldom appears where the contents of the abdomen have been removed.
Orders Neuroptera, Hymenoptera and Diptera. The Dragon Flies (Libellulce) are frequently very difficult to kill, being powerful and nervous animals. When caught they should be transfixed through the sides, and it sometimes becomes necessary to put braces on their wings to prevent them from fluttering while in the hunting, box. They may also be killed sometimes by placing them under a tumbler and suffocating them. Some entomologists put them in scalding water for an instant. The contents of the abdomen should always be removed from Dragon Flies, otherwise it will become black and shining through the skin, and destroy the beautiful bands with which they are ornamented. They can be stuffed with cotton or a small roll of paper introduced. If these precautions are attended to, the insect will preserve the perfect beauty of its living state.
The other species of these orders soon die after being transfixed. They may be set by braces and pins, as represented in Figs. 35 and 37.
Some of the Dipterous insects are very perishable in point of color after death, particularly in the abdomen, the skin of which is very thin. The only way of remedying this is to pierce the abdomen, and after taking out the contents the cavity should be filled with a powdered paint the same color as the living subjects, which will shine through and give it all the appearance of nature.