Mounting and Preserving Insects

Most insects are preserved dry, normally on pins, and once dry will keep indefinitely. Soft-bodied insects must be preserved in liquids, since they shrivel or become distorted if preserved dry. Minute insects that are hard-bodied may be mounted (dry) on "points," but many must be mounted on microscope slides for detailed study. Insects that are preserved dry should be pinned or mounted as soon as possible after they are collected; if allowed to dry first they become very brittle and may be broken in the process of mounting.

Relaxing Specimens. Dried specimens can be relaxed by placing them in a humid atmosphere for a few days; any airtight jar can be used as a relaxing chamber. Cover the bottom of the jar with wet sand (add phenol or ethyl acetate to prevent mold), put the insects into the jar in small open boxes or envelopes, and close the jar.

Pinning. Insects sufficiently hard-bodied to retain their shape when dry, and big enough to pin, are normally preserved by pinning. Common pins are too thick and too short, and they rust; insects should be pinned with insect pins, made especially for this purpose, which can be bought from a supply house. They are available in various sizes (thicknesses). The best sizes for general use are Nos. 1 (very slender), 2 (less slender), and 3 (thicker, for larger insects).

Most insects are pinned vertically through the thorax; a few are pinned sideways. Beetles and hoppers are pinned through the front part of the right wing, at a point where the pin on emerging from the underside of the body will not damage a leg. Bugs are pinned through the scutellum (p. 33) if it is large enough to take a pin or through the right wing, as for beetles. Grasshoppers and crickets are pinned through the rear edge of the pronotum, just to the right of the midline. A treehopper is pinned through the pronotum just to the right of the midline. Dragonflies and damselflies can be pinned vertically through the thorax with the wings horizontal, but it is better to pin them sideways, left side up, with the wings together above the body, the pin going through the thorax below the wing bases. If the wings are not together when the specimen is removed from the killing jar, place the specimen in an envelope (the wings together above the body) for a day or two until it has dried enough for the wings to stay in this position; then pin it.

The simplest way to pin an insect is to hold it between the thumb and forefinger of one hand and insert the pin with the other hand. All specimens and labels put on a pin should be at a uniform height; this is most easily accomplished with a pinning block.

How insects are pinned. The black spots show the location of the pin in the case of flies (A), beetles (B), bugs (C), grasshoppers (D), dragonflies and damselflies (E), and leafhoppers, froghoppers, and planthoppers (F).

Pinning blocks. These may be made of a rectangular piece of wood (A) or one shaped like steps (B), with holes drilled to 1, and Y% in. After placing a specimen on a pin, insert the pin in the 1-in. hole until it touches bottom. The Y%-in. hole is used to position the locality-date label on the pin, and the %-in. hole to position a second label, if there is one.

Mount the insect about an inch up on the pin. With large-bodied insects there should be enough of the pin above the insect to permit easy handling.

Sagging of the abdomen of a pinned insect (like a dragonfly) can be prevented in the following ways: (1) by sticking the pinned specimen onto a vertical surface, with the abdomen hanging down, and leaving it there until the abdomen dries; or (2) by placing a small piece of cardboard on the pin, just under and supporting the insect, and leaving it there until the insect dries; or (3) by supporting the sagging abdomen with crossed pins, the abdomen resting in the angle where the pins cross.

A sheet of cork, balsa wood, or other soft material is useful for the temporary storage of pinned specimens until they can be sorted and placed in boxes.

Mounting Small Insects on Pins. Insects hard-bodied enough to mount dry but too small to pin are usually mounted on "points." Points are small triangular pieces of cardboard, about 8 mm. long and 3 or 4 mm. wide at the base; the pin is put through the base of the point and the insect is glued to the tip. Points can be cut with scissors or punched out with a special punch (obtainable from a supply house), or they can be purchased from a supply house.

Mounting small insects on points. A, beetle, dorsal side up; B, fly, left side up; C, beetle mounted dorsal side up, attached by its side to the bent-down tip of the point.

Insects put on points should be glued so that the body parts to be examined in identifying the insect are not obscured. The best position for an insect is on its right side, with the head away from the pin (B, above). Flat insects that may be difficult to mount on their side are usually mounted dorsal side up at the extreme tip of the point.

Place an insect that is to be put on a point at the edge of a block,

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