Earwig

Common Name: Earwig
Scientific Name: Order Dermaptera

Introduction. The common name of earwig comes from an old European superstition that these insects enter 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.

Recognition. Adult earwigs measure 1/4 to 1 inch long, and have an elongate, flattened body. They are colored pale brown with dark markings to uniformly reddish brown to black, but with paler legs. Earwig adults usually have 4 wings. The front wings are leathery, short, and meet in a straight line down the back; whereas, the hind wings are membranous, fan-shaped, and are kept folded under the front wings. The cerci are well developed and forceps-like but usually differ in shape in the sexes. The antennae are threadlike, and about half the length of the body. Earwigs have chewing mouthparts. Nymphs are similar to adults but have no wings.

Similar Insects. (1) Rove beetles (Coleoptera: Staphylinidae) and other beetles with short elytra (wing covers) are much like earwigs in size and body shape but lack the forceps-like cerci. (2) Cockroaches (Order Blattodea) have short feeler-like cerci and a large, shield-like pronotum that extends over the head.
Representative Species. The European earwig, Forficula auricularia (Family Forficulidae) is the most common pest species and is abundant in the Midwest. Adults are about 5/8 inch long, including the forceps. Some males are considerably larger with forceps-like cerci of about 1/4 inch while other males have forceps of about 3/8 inch long. They are dark reddish-brown with reddish head and paler wing covers, legs, and antennae.
Biology. Earwigs typically overwinter outdoors as adults in protected situations. The European earwig overwinters in pairs in earthen cells 1 1/8 to 1 1/2 inches beneath the surface. The females lay and tend their eggs in these underground situations and then the newly hatched nymphs. Earwigs have 4 to 5 nymphal instars (immature growth stages). Nymphal development averages about 68 days for the European earwig and includes 4 instars. European earwig females lay about 30 to 55 eggs the first batch and many fewer the second time. The nymphal instars require about two months to complete development. Some females may live as long as 7 months after attaining maturity.
Earwigs have a distinctive disagreeable odor, which is released when they are crushed, but some species can squirt such a liquid. They are gregarious in nature, typically occurring in groups.

Habits. 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 and dead plants and tiny insects. At times they damage cultivated plants. The European earwig occasionally damages vegetables, flowers, fruits, ornamental shrubs, and trees, and has been recorded as feeding on honey in beehives.
Earwigs are attracted to lights or to insects attracted to lights. European earwigs often invade homes, sometimes by the hundreds or thousands. They may enter weep holes through brick facing and beneath siding along the foundation. They also bridge from tree and shrub branches in contact with building surfaces.

Cultural Control & Preventative Measures. 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. Since earwigs enter buildings beneath siding and through weep holes, utility penetrations and crevices in the foundation, some reduction in their numbers indoors can be achieved as a result of thorough exclusion efforts using silicone sealer, construction putty, mortar patch compound, and copper gauze as filler materials.
A vacuum cleaner and well-placed pest sticky traps can be used to capture earwigs indoors and in attached garages.

Professional Control. A Rottler technician will apply an exterior barrier treatment using residual liquid insecticide around the foundation perimeter, beneath lower siding, along exterior molding/trim, thresholds, patio and deck attachments. Residual liquid and/or granular insecticides or granular insecticide baits may be use to treat mulch and landscaping features located close to the foundation, as well. A quarterly pest management service program may be required in cases where large populations of earwigs are present and where landscaping conditions and locality are conducive to their propagation.