Killing Insects. — Having caught your butterfly, you will wish to kill it in the most painless and least troublesome manner. For this purpose you will require a "cyanide bottle." Purchase, therefore, at the druggist's a wide-mouthed bottle (a 4 oz. bottle is a handy size for the pocket, but you will require larger sizes for certain uses). Into this bottle put from an ounce to an ounce and a half of pure cyanide of potassium, in lumps, not pounded (a deadly poison), which you will completely cover with a layer of plaster of Paris, mixed to the consistence of paste. The bottle may be corked, have a screw top, or glass stopper, according to your fancy. A glass stopper is, of course, the safest to confine the deadly vapour given off, but in point of convenience, and especially for outdoor work, nothing can surpass a well-fitting cork — rising sufficiently high above the mouth of the bottle to afford a good grip. As the plaster is setting it should be well shaken down to insure an even surface, and afterwards a piece of wool or blotting-paper should be put into the bottle to absorb any superfluous moisture. In the course of a day, the plaster will be dry and ready for use. [Footnote: A piece or pieces of blotting-paper cut to fit will be found very handy to introduce into the bottle from time to time to absorb all moisture, and to keep the specimens themselves mean and dry.]
Fig. 45 — The "Hill sliding net" ready for use.
The insect being captured, you twist your net rapidly over to get it as near to the bottom as possible — a very necessary precaution in the case of a swift-flying or excitable insect. Holding the net now in the left hand, take the bottle, previously uncorked, in your right hand and slip it into the net and over the insect. In case of refractory insects, blowing from the outside will sometimes make them go to the bottom of the bottle. When this happens, you can slip your hand from the outside over the mouth of the bottle, and hold it there until the insect is corked up. In less than a minute it is stupefied and motionless. If taken out, however, it will revive; it must be left in, therefore, from ten to fifteen minutes. In the case of female insects which have not yet deposited their eggs, and are consequently exceedingly tenacious of life, a longer time will be found necessary.
Bruised laurel leaves, chloroform, benzol, etc.., are recommended by some authors. The first is, I think, uncertain in its effects, and has, perhaps, a tendency to make the insects go ultimately mouldy. The second stiffens the wing rays of some insects to such an extent as to render them difficult to set. It has been recommended in the case of large insects, such as the hawk moths, to pierce them underneath the thorax at the insertion of the first and second pairs of wings with a steel pen dipped in a saturated solution of oxalic acid. I have frequently done this myself with good results in the days when cyanide bottles were unknown, but for the largest hawk moths -- "Death's heads" even — I find nothing to beat a large bottle (a glass jar, such as the French bottle plums in, does admirably), in which is placed about 0.25 lb. of cyanide. With a killing jar of this kind, which I call the "home" bottle, I have frequently instantaneously killed mice and even rats. In fact, the volume of poisonous vapour evolved from one of these bottles is such, that I advise my readers not to take "sniffs" therefrom, lest severe headaches, or worse results, should follow.
As it is nearly all but impossible to pin an insect so correctly as you would wish during the hurry and excitement of butterfly hunting, I recommend that all insects captured when the collector is from home be laid on their sides, and the pin passed through the body whilst in that position. This saves the unnecessary marking of the thorax by more than one pin hole, as the pin can be removed without detriment to the formation of the body, and the insect pinned in its proper position when the collector reaches home.
SETTING. — Having brought the entomologist to this point, I may discuss what to do to preserve the trophies of the day's chase. First, then, the insects must be "set." To do this properly is the vexata quaestio of the day. As a nation we anciently practised the "setting" of lepidoptera with four or eight braces, two or one underneath and two or one on top of the wings. The wings were then not so fully extended as now, but the body was pressed as close to the setting board as it was possible to get it. The next step was the cork setting board, cut to show in section nearly a half oval, the bodies were a little raised from the set, and the rounded points of the fore and hind wings invariably touched the paper of the cabinet when placed therein, curling up wherever they touched.
