Dermaptera

Earwigs are tropical insects that can be found all over the world with the exception of the polar regions. Earwigs undergo incomplete metamorphosis.  Female earwigs care for her eggs and young.  The nymphs become independent when they are halfway to adulthood.  The nymphs go through four to five instars (molts) before becoming an adult.  Earwigs feed on fungi, decaying material, or dead insects depending on the species.  They are omnivorous, but some species are ectoparasites to vertebrates.  They can be found under bark or stones.  They are nocturnal with antennae and forceps.  There are winged and wingless varieties in the Order Dermaptera.  If threatened, they emit a fluid with a terrible odor to ward off potential predators.  Earwigs can be found in the fossil record as far back as the Jurassic.

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 (some species 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.

(Haas 1996)

Earwigs are found in temperate regions to the tropics and subtropics. Of the approximately 1,800 species that exist worldwide, 28 species are found in the United States, and 6 species are found in the Great Lakes region. Those in the Great Lakes region are introduced from southern areas.

Biogeographic Regions: nearctic (Native ); palearctic (Native ); oriental (Native ); ethiopian (Native ); neotropical (Native ); australian (Native )

These nocturnal insects hide in cracks, crevices, under bark, and in debris during the day. If present in sufficient numbers, earwigs can be found hiding almost anywhere in the homes of humans.

Habitat Regions: temperate ; tropical ; terrestrial

Terrestrial Biomes: desert or dune ; chaparral ; forest ; rainforest ; scrub forest

Wetlands: marsh ; swamp ; bog