Essays on the Microscope / Containing a Practical Description of the Most Improved Microscopes, a General History of Insects, etc., etc.

by George Adams

THE METHOD OF COLLECTING THEM IN THEIR FLY OR PERFECT STATE.

The extreme delicacy of the wings of moths and butterflies will not admit of their being caught without injury, but in nets made of the finest materials. It will be necessary, therefore, that the collector should provide himself with a net properly adapted to this purpose: the one [here] represented has, after long experience, been found to answer extremely well. Fig. A shews the net expanded ready for use; a exhibits the part made of fine Scotch gauze, which should be previously dyed green; b b, the sticks; these should be of some light wood. To render them compact and convenient for carriage, they are made to take to pieces somewhat in the manner of fishing-rods, and connected by means of screws or hollow brass ferrils fixed to the end of each: there are three of them for each side of the net. Fig. B shews one of the sticks; a, the brass ferril; b, the end of the next stick, which fixes tight into it; to the upper end of the sticks, at c, is joined in like manner a piece of cane bent to a proper shape. Instead of three pieces of wood, as here described, the other stick may consist of one entire piece, and be used as a walking-stick. The gauze must be edged with two pieces of binding sewed together, to receive the sticks when joined; and, as the sticks are taper, so must be the cavity to receive them. At the lower part the gauze is to be turned up about six inches, so as to form a bag, Fig. A, c. At the extremity of the gauze, next the handles, two pieces of tape must be fixed on each side, d d, of sufficient length to pass through a hole bored in the stick, and then be tied in a loop, so as to prevent the gauze from sliding on the sticks. At the upper part of the net where the canes meet, e, the cavity should be closed by a few stitches, that the sticks may shut even together. The net may be about a yard in width when expanded, and the length of it a yard and an half: the size, however, may be varied at pleasure. The gauze should be deprived of its glazing by being soaked for a short time in warm water; but, if dyed green, which is usually the case, this will be unnecessary. The handles are to be held one in each hand, when the net is used.[161]

[161] Though this net be principally intended for catching moths and butterflies on the wing, it maybe usefully applied to another purpose: if one person expand the net under a bush or branch intended for examination, and another shake the bush, or beat it well with a stick, numbers of caterpillars, as well as some of the minuter kinds of coleopterous, and other insects, will fall into the net. By these means moths are likewise often taken, as they remain in a torpid state during the day, sheltered in the bushes.

Besides the gauze net for catching butterflies, &c., the collector should be provided with a pair of forceps, made of steel, about nine or ten inches in length, and of the shape represented in the figure;[162] the fans are to be covered with fine green gauze. This instrument will in many instances be found exceedingly commodious, as being of more general use; it is very portable, and possesses this advantage over the net, that the insect caught in it will be more confined, and consequently not so liable to injure its down. If the insect be met with on the trunk of a tree, paling, or any flat surface, it may be readily caught; if on a leaf, both may be enclosed in the forceps. Whilst in the forceps, it should be pressed with the thumb, or, if the creature be small, with the thumb-nail, sufficient to stupify, but not crush it.

[162] This figure shews the forceps in the proportions in which they have been generally made; I would, however, recommend the fans to be considerably larger, and the handles shorter. The form of the fans has commonly been either hexagonal, or, the worst of all, triangular; experience has taught me that the shape as here given is to be preferred, as being less liable to miss the insects, who are usually upon their guard, and frequently elude the vigilance of their pursuers. A front view of the fans is given, the better to shew their form; but it is obvious that they must be placed in a contrary direction, so as to flap on, not slide over, each other.

The next articles necessary to be provided, will be two or three oval chip boxes, cut sufficiently flat for the pocket, and lined at top and bottom with thin cork; and a cushion well stored with pins of various sizes.

The collector being now furnished with the necessary instruments, it will be proper to give him such instructions as may enable him to use them. With regard to the manner of using the net with expertness and success, this knowledge will be much better acquired by practice than by the most ample description. Harris, in his elegant work, The Aurelian, has been rather diffusive than clear on this subject. Having caught the butterfly or moth in the net, it will be necessary to proceed with caution, as on killing it properly its beauty in a great measure depends. It should not be laid hold of indiscriminately in any part; but by managing skilfully the net, its wings must, if possible, be brought into an erect position or close together; then press the under part of the thorax or breast between the thumb and the fore-finger sufficiently hard to kill the insect. By carefully attending to these directions, the wings will not be distorted or the plumage injured.

The net being now opened, the insect is to be laid hold of by one of its antennæ or horns, and again placed between the thumb and fore-finger; in which situation it is to be held, while a pin proportioned to its size is stuck through the upper part of the thorax or back; it may then be affixed to the pocket-box by sticking the point of the pin into the cork lining. The larger kinds of these insects, especially moths and hawk-moths, which are far more tenacious of life than butterflies, will not expire so readily by this method, as by fixing them upon the bottom of a cork exactly fitted to the mouth of a bottle into which a little sulphur has been put; by gradually heating the bottle till an exhalation of the sulphur takes place, the insect usually dies without injuring its colour or plumage.