The earwig is a slender insect of the order Dermaptera, with a pair of forcepslike cerci, or pincers, at the tip of the abdomen. If an earwig is handled, the cerci may grip the skin, but they are not able to pierce it. Possibly the cerci are used to assist in folding the very complicated hind wings, which are semicircular, with supportive veins radiating out in fanlike fashion. When folded, the hind wing is packed way underneath the fore wing, which is reduced to a short, leathery cover. Earwigs rarely fly, perhaps because it is so difficult to stow away the wings. Some wingless earwigs parasitize bats and rats.
It has been suggested that the name "earwig" may be a corruption of "ear wing," a reference to the peculiar type of wing. More commonly, it is believed that the name is derived from the habit attributed to these insects of crawling into the ears of sleeping people. Though now generally discredited as an old superstition, this idea is not without some grounds. Earwigs are nocturnal creatures and spend the day concealed in crevices. They display a reflex orientation (thigmotaxis) to tactile stimuli, or touch, that compels them to squeeze into narrow spaces.
Earwigs have chewing mouthparts and eat either animal or vegetable food. Some forms are predatory and will catch flies and other insects, but earwigs are chiefly scavengers of decaying material. They occasionally feed on living plants and may cause some damage in gardens or greenhouses. A nonpesticide method of control is to clear away plant debris under which the earwigs can hide and then to set up "earwig traps," consisting of flowerpots lightly stuffed with straw, into which the earwigs will crawl at night.
The reproduction of earwigs is of special interest because they practice an elementary form of maternal care. The female lays her eggs in a burrow in the ground and guards them until they hatch, even turning them over from time to time. The young, called nymphs, pass through four to six stages, or instars, before reaching maturity.
There are over 1,000 species of earwigs in the world, 20 of which occur in North America. The native American earwigs, however, are seldom seen. The most familiar European earwig, Forficula auricularia, has been introduced by man into the United States, where it is likely to become a minor horticultural pest as it is in Europe.