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Contributors: C.S. Apperson, Extension Entomology Specialist; J.R. Baker, Extension Entomology Specialist; L.Garcia, Entomologist, Plant Protection Section, NC Department of Agriculture; M.G. Waldvogel, Extension Entomology Specialist.

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Earwigs

Order: Dermaptera
Family: Labiduridae
Scientific Name: Ringlegged Earwig, Euborellia annulipes Shore Earwig: Labidura riparia.

Description

Adult. These brown to black, elongated insects, 19 to 25 mm long, have a pair of large forceps at the end of the abdomen. Forceps of females are almost straight; those of males curve noticeably. Adults may or may not have wings. If present, forewings are short, thickened, and veinless, and cover the membranous hind wings. Earwigs rarely fly when disturbed. Deposited in clusters, eggs are at first smooth, white, and ovate. Before hatching, they become brown and kidney-shaped. Individual eggs are approximately 1 mm long and 0.8 mm wide.

The grayish nymphs are wingless and smaller than adults, although similar in shape. The nymph's body has a 10-segmented abdomen. The antennae gain segments in progressive instars. The forceps of both sexes are straight.

Biology

Earwigs occur throughout North America, but tend to be more common in the southern and southwestern states. Few earwigs successfully overwinter outdoors in northern states. The earwig diet is highly variable. European earwigs feed at night on the foliage of various flowers and garden plants. Most species prey on other insects and supplement their diet with decaying organic matter found in soil or garbage. In addition to consuming aphids, beetle larvae, and maggots, earwigs also eat seeds of grain.

Earwigs are essentially beneficial insects that prey on more harmful insects. Though large populations may do direct damage to grass by feeding on it, earwigs are mainly a nuisance pest just because of their presence. They crawl into anything that is on the ground- a garment, golf bag, flower pot, etc -and then come in contact with the people involved. If trapped or touched, earwigs pinch the offender with their forceps.

Earwigs are nocturnal pests that hide from light and feed at night. In central and southeastern states, they overwinter in all stages under stones or debris or in other protected places. During cold winters, they are likely to invade greenhouses, sheds, and houses.

Ringlegged earwig females deposit in several batches, an average of 47 eggs. European earwig females, on the other hand, lay 50 to 90 eggs. Eggs deposited in the soil in fall usually overwinter; those laid in spring incubate at least 14 days before hatching. The mother guards her eggs, eating any fungi that start to grow on them and protecting them from predators. A few days after emerging from eggs, nymphs leave the nest. Nymphs feed and develop through five instars over a period of 45 days in warm months or up to 176 days during winter. Three out of every four nymphs develop into females. Mating takes place soon after adult emergence; the first eggs are deposited about 11 days later. Earwigs complete only one generation each year, but since broods overlap, all life stages are present at any given time.

Control

Control of earwigs is usually not necessary. Their low reproductive potential usually ensures the success of control efforts. On turf that has been sprayed for other pests, earwigs are rarely a problem. For specific insecticides and rates, consult the current North Carolina Agriculture Chemicals Manual for recommendations.

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