How to Collect and Preserve Insects

by Herbert H. Ross

Preservation by Pinning

Hard-bodied insects, such as beetles, flies, and wasps, are preserved as dry specimens on pins better than in fluid. The pinned specimens are more convenient to study and they retain their natural coloring better. Flies and butterflies are covered with hairs or scales that clot or break off if the specimens are preserved in fluid, and for this reason they should be pinned.

Fig. 11.—Pinning. Medium- to hard-shelled insects are mounted by being pinned through the body in the manner shown at a. The black spots show the location of the pin in the case of bees, flies, and wasps, b; stink bugs, c; grasshoppers, d; and beetles, e.

Common household pins are too thick and short for pinning insects. Longer, slender pins called insect pins are necessary and may be purchased from various supply houses. They should be of spring steel; a brass pin will corrode and be destroyed by acids in the insect’s body. The pins are available in numbered sizes, of which 1, 2, 3, and 4 will be found of most general use, and sizes 0 and 00 of advantage in special cases.

Medium to Large Insects.—Medium to large hard-shelled insects such as moths, beetles, flies, bees, and wasps, should be pinned vertically through the body, [fig. 11]a. It is essential that the pin pass through a fairly solid part of the body, and, to insure this, the following standard procedures should be adopted:

1. Bees, wasps, flies.—Pin through thorax between bases of front wings slightly to right of middle line, [fig. 11]b.

2. Stink bugs.—Pin just to right of middle line of the scutellum or large triangle between the bases of the front wings, [fig. 11]c.

3. Grasshoppers.—Pin through back part of prothorax (the saddle behind the head) just to right of middle line, [fig. 11]d.

Fig. 12.—Pinning. Moths, a, and butterflies, b, are pinned through the center of the thorax (instead of to the right of the median line) between the bases of the front wings.

Fig. 13.—Pinning block. The block is 1¼ × 1¼ × 2¼ inches, with holes drilled to the depths shown and having diameters only slightly greater than the largest pin that will be used. A specimen is pinned and the pin inserted into one of the holes until the pin touches bottom; thus, insects may be pinned uniformly at a desired height.

4. Beetles.—Pin near front margin of right wing cover near middle line, [fig. 11]e.

5. Moths, butterflies, dragonflies, damselflies.—Pin through the center of the thorax between the bases of the front wings, [fig. 12].

The insect should be pushed about three-quarters of the distance up the pin, but not so close to the top that no room is left for easy handling of the pin with the fingers. It is well to have all insects the same distance from the top of the pin. To insure a uniform distance, the collector should use a pinning block. This is a small piece of wood or metal usually in the form shown in [fig. 13], into the top of which are drilled holes slightly larger than the pin diameters. Such a block may be fashioned of wood with holes made by small nails and covered with a cardboard rectangle through which have been stabbed holes the exact size of those in the wood. The depths of the holes in the block should be three-eighths inch, three-quarters inch, and 1⅛ inches, respectively. To use the block, pin the insect and insert the pin into whichever hole allows the specimen to be pushed up the pin and still leave room, allowing for the thickness of the insect’s body, for handling at the top.

Fig. 14.—Pinning small insects and labeling. The insect may be glued to a card point, a, which has been crimped to meet the right side of the body, b, c; or it may be pinned with a minuten pin, d, to a piece of cork or pith, which in turn is regularly pinned. All pinned insects should be labeled, as at e. In the case of some small insects, such as tiny moths, the minuten pin may be run down through the body and then into the cork; in the case of others, such as mosquitoes, it is often desirable to run the minuten pin up through the cork first and then impale the specimen on the point of the pin.

Tiny Insects.—Very small insects should be mounted on card points or on minuten pins. Regular pins would break too many of the insects’ body parts.

Card points are small triangles of cardboard or plastic pinned through one of the sides and crimped over at the opposite apex; a spot of strong glue is put on the angled tip, and the right side of the insect is pressed against the glued surface, [fig. 14]. The slant of the crimp depends on the angle of the insect’s side; the desired product is the insect mounted with its top surface horizontal and its head forward; legs, wings, and antennae should be in view and as little of the body as possible hidden by the glue or card point. Very little glue should be used; a small amount holds well and gives a better specimen for study than a large amount. The points may be cut uniformly with a hand punch, and they should be about three-eighths inch long. Good material for making these points is 2-ply Bristol board.

Fig. 15.—Pinning crane flies. Because of their unwieldy legs, these insects should have a double card point mount, and the legs should be kept away from the pin so that they will not be broken in handling.

Minuten pins are short, extremely delicate steel pins, [fig. 14]d. One of these is thrust through the body of the insect and into a small piece of cork, pith, or similar substance, which is in turn pinned in the regular way a card point is. This method is especially desirable for tiny moths.

Insects Hard to Pin.—Wasps, lacewings, damselflies, and similar insects have an abdomen that sags readily when the specimen is killed and pinned. This unwanted drooping can be prevented in three simple ways. (1) Stick the pinned insect on a vertical surface of a block so that the body by its own weight dries in normal position. (2) Pin the insect on a horizontal surface and run a stiff paper on the pin beneath the body in such a way as to support it in a natural position until the insect dries. (3) Brace the abdomen by crossing two pins beneath it and thrusting them into the block, allowing the specimen to dry in the angle of the cross.

Crane flies are unwieldy and so are best pinned on a double card point mount, [fig. 15]. The legs should be directed away from the pin to avoid breakage in handling.