Earwigs fold hidden wings under short covers and raise young
Earwigs form the modest order Dermaptera—about two thousand species—with forceps-like cerci and wings tucked under stubby forewings. Most hunt and browse at night from moist crevices. Females of many species guard eggs and young nymphs, rare maternal care among insects.
Five molts precede adulthood; sexual dimorphism in the pincers grows across molts. Living forms are Neodermaptera from the Cretaceous; older Archidermaptera and Eodermaptera fossils reach the Triassic and Jurassic. Charles De Geer coined Dermaptera (“skin wing”) in 1773; English earwig joins Old English ear and wicga, an insect. They hide by day and feed at night on both insects and plants, and gardeners often blame the common earwig, Forficula auricularia, for chewed leaves, flowers and crops. Some tiny groups live as parasites on mammals and lack pincers altogether.
The common earwig arrived in North America from Europe in 1907 and is commonest in the southern and southwestern United States; the only native species in the north is the spine-tailed earwig, which hides in the leaf axils of young wetland plants as far as southern Ontario. Few earwigs survive winter outdoors in cold climates. Roughly twenty-five species inhabit North America, forty-five Europe, sixty Australia. Bodies stay flat, usually 7–50 mm; Australia’s Titanolabis colossea nears fifty millimeters. Entomologists think the name refers to the unfolded hindwing, which looks like a human ear, but folklore links it to a tale of earwigs tunnelling into people's brains through the ear; they are not known to seek out ears, though at least two anecdotal cases exist. Among Polyneoptera, they branched off early alongside angel insects and stoneflies.
The pincers do triple duty, catching prey, fending off attackers and tucking the fan-like hindwings under the leathery forewings, a folding pattern unique among insects. Males usually have more strongly curved pincers. Most earwigs can fly but seldom do, and a few groups living on other animals are wingless and blind. Saint Helena's giant earwig, declared extinct in 2014, reached 78 millimetres. Males in six families carry paired penises, but since females have one genital opening only one is ever used, and unlike other insects the female opening sits behind the seventh abdominal segment.
Source: Earwig
