Insects in the order Dermaptera are commonly known as earwigs. Roughly 2000 species of earwigs have been described. Earwigs are elongate and slender insects that are typically brown or black (although other colors, such as metallic green, are seen in a few species) and have the front pair of wings reduced and leathery (in some species, they are are wingless). The abdomen is very flexible, with a pair of unsegmented (and usually forceps-like) cerci at the tip. Body length, including cerci, ranges from around 4 mm to 80 mm (the giant being the St. Helena Giant Earwig, Labidura herculeana). Earwigs are found throughout the world (with the exception of polar regions), but are most diverse in the tropics.
Most earwigs are omnivorous, but predominantly phytophagous (plant-eating) or predacious species are also known. Some species live on decaying material. The Hemimerina is a group of around 10 known species of wingless and blind live-bearing earwigs that live on giant tropical African rats and feed on skin flakes and fungi on the rats without harming them. The Arixenina includes around 5 known species of wingless and nearly blind live-bearing earwigs that live on bats in the Malay Archipelago and feed on their skin gland secretions and occasionally on dead insects.
Earwigs are positively thigmotactic (i.e., they like to be tucked into cozy spaces) and frequent (humid) crevices of all kinds, such as under bark, between leaves, and beneath stones. The behavior of earwigs is complex and the cerci often play an important role. They are used to open the wings, to capture prey, and for defense. Females show maternal care (probably in all species, although only a few have actually been studied). In contrast to the live-bearing Hemimerina and Arixenina, members of the third earwig group with living representatives, the Forficulina (which includes nearly all known earwig species), are generally oviparous (egg-laying).
The idea that earwigs enter people's ears is an old myth.
An excellent resource on earwigs, including species checklists for many countries, is the online Earwig Research Centre.