Common Name: Earwig
Scientific Name: Various
Class / Order / Family: Insecta/Dermaptera/Various
The common name of “earwig” comes from an old European superstition that these insects enter the ears of sleeping people and bore into the brain. This belief is without foundation. The forceps like cerci are apparently used as both offensive and defensive weapons, and are sometimes used to capture prey. Earwigs are worldwide in distribution, with about 22 species occurring in the United States.
Adults about 1/4-1″ (5-25 mm) long, with body elongate, flattened in form. Color varies from pale brown with dark markings to uniformly reddish brown to black, but with paler legs. With 4 wings (rarely wingless), from wings leathery, short, and meeting in a straight line down the back whereas, hind wings membranous, fan-shaped, and folder under front wings. Cerci well developed and forceps like but usually differ in shape in the sexes. Antennae threadlike, about half body length. Tarsi 3-segmented. Mouthparts chewing. Nymphs similar to adults but have no wings.
(1) Rove beetles (Coleoptera: Staphylinidae) and other beetles with short elytra (wing covers) lack forceps like cerci.
(2) Cockroaches (order Blattodea) have short feeler like cerci, 5-segmented tarsi.
1. The European earwig (Forficula auricularia Linnaeus, family Forficulidae) is the most common pest species. Adults are about 5/8″ (16 mm) long including forceps. Some males are considerably larger with forceps like cerci of about 1/4″ (5 mm) while other males have forceps of about 3/8″ (9.5 mm) long. They are dark reddish brown with reddish head and paler wing covers, legs, and antennae. Antennae 12-segmented. The 2nd tarsal segment is broadly lobed, prolonged beneath the 3rd segment.
2. The red-legged earwig (Emborellia annulipes (Lucas), family Carcinophoridae) is a native American species which is common in the south and southwest. It is a wingless species. Adults are usually about 1/2-5/8″ (12-15 mm) long but may reach about 1″ (25 mm). They are dark brown to black with a yellowish brown undersurface. The yellowish legs have femora and tibiae ringed with brown stripes. The antennae are about 16-segmented and black, but the 3rd, 4th and usually the 5th segments from the apex are yellow to white. The 2nd tarsal segment is cylindrical. The male’s forceps like cerci are distinctly asymetrical, the right member much more strongly curved than the left.
3. The striped earwig (Labidura riparia (Pallas), family Labiduridae), also called the shore or riparian earwig, is a second species common in the southern and southwestern states. Adults are about 3/4-1″ (20-25 mm) long. The color varies from pale brown with indistinct darker markings to chestnut or reddish brown with indistinct paler or darker markings to black. The abdomen is usually banded and the cerci are usually darker at the tips. The 2nd tarsal segment is cylindrical. The male’s forceps like cerci are symmetrical, usually long and distinctly toothed while others are shorter and weakly toothed.
Earwigs typically overwinter outdoors and adults in protected situations. The European earwig overwinters in pairs in earthen cells 1 1/8-1 1/2″ (30-40) mm) beneath the surface and the striped earwig in subterranean burrows or chambers. The females lay and tend their eggs in these underground situations and then they tend the newly hatched nymphs. Earwig have 4-5 nymphal instars. Nymphal development averages about 56 days (range 40-60) for the striped and takes about 68 days for the European earwig, both having 4 instars.
European females lay about 30-55 eggs the first batch and fewer the second time. The striped female lays about 50 eggs the first time ad may lay 3-4 more batches. The red-legged female lays about 40-53 eggs on the average and its 5 nymphal instars require about 80 days to complete development. Some females may live as long as 7 months after attaining maturity. Earwigs have a distinctive disagreeable/repugnant odor which is released when they are crushed, but some species can squirt such a liquid. The are gregarious in nature, typically occurring in groups. Red-legged earwig have been reported to cause minor skin abrasions in humans.
Earwigs are nocturnal or active at night and hide during the day in moist, shady places such as under stones or logs, or in mulch. Neither the eggs nor nymphs can withstand long periods of dryness. Earwigs feed on live or dead plants and/or insects. At times they damage cultivated plants. The European earwigs occasionally damage vegetables, flowers, fruits, ornamental shrubs, and trees, and has been recorded as feeding on honey in beehives.
The red-legged earwig has been recorded as a pest of Irish and sweet potatoes in storage, damaging the roots of greenhouse vegetables, and as a pest in flour mills, breweries, meat-packing plants, slaughter houses, gardens, and nurseries. The striped earwig has not been recorded as damaging plants. Earwigs are attracted to lights or to insects attracted to lights. Usually it is the European and red-legged earwigs which occasionally invade homes, sometimes by the hundreds or thousands.
The key to control is the removal of unessential mulch, plant debris, and objects such as stones and boards, from around the structure. The purpose of this is to establish a low-moisture zone which is disagreeable to earwigs. Micro encapsulated and wettable powder residual formulations applied as 3-10 foot (1-3 m) band treatments are particularly effective. Baits are very effective. Indoor control is supplemental to the outdoor control measures.