Most adult insects in collections are mounted on pins. Most medium-sized to large insects, such as grasshoppers, butterflies, moths, flies, bees, and many beetles should be pinned directly through the body from top to bottom. Many small insects, such as leafhoppers, plant bugs, small beetles, and the like, should be glued on card points. Immature insects and the adults of some groups are best preserved in fluid.
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.