Earwig (Forficula auricularia
, Linnaeus 1758) is normally intercepted in bundles of plants, shrubbery
, cut flowers and florists' equipment arriving from the Western United States
. Man largely spreads the insect as it has only a limited ability for flight
. The earwig was first recorded in Newport, Rhode Island
in 1911. By 1915 a small colony was reported in Seattle
, Washington. Later evidence indicates that despite its European origins, it first invaded North America
on the western coast in the early 1900's before becoming widespread in the New England
and Middle Atlantic states. The Earwig is most abundant where adequate rainfall or irrigation
provide moisture and food. The name earwig springs from an unfounded myth
that it lodges in the ear causing any number of folk tale
ailments. In reality the Earwig, despite its fearsome appearance, is harmless to humans, but has a powerful scent gland
that can release a foul odor when crushed.
The earwig is found throughout Europe but seldom in great numbers. While it has not become a serious economic threat in its homeland, it has become quite a pest in many parts of the United States.
Originally from the palearctic region, the earwig has been found in quantities in Canada (British Columbia, Manitoba, Newfoundland, Nova Scotia, Ontario, Quebec and Saskatchewan) and the United States (Arizona, California, Colorado, Idaho, Maine, Massachusetts, Montana, New York, North Carolina, Oregon, Rhode Island, Utah and Washington). Dr Kevin M. Hoffman from the Department of Entomology at Clemson University reports unpublished colonies in Kansas, Maryland, Nebraska, New Hampshire, Ohio, Pennsylvania and Wisconsin. There is a questionable record for an appearance in Chile.
F. auricularia is a medium sized insect with a body length averaging between 12-15mm. The males have forceps from 4-8mm while the females are about 3mm. Male forceps vary from about half as long to as long as the upper abdomen, broadened at the basal end with crenulated teeth basally and on the beginning curvature of the inner margin. Antennae are segmented 14 to 15 times. The adult is a reddish brown with wing covers and legs being a yellowish hue. Males are distinguishable from other North American varieties of Earwig by their distinctive forceps.
Life History and Habits
The female lays between 50 and 90 eggs about 5-8mm below the surface of soil in the fall. The eggs are a shiny white about 1.5mm in length. Rich garden soil with a southern exposure is a favored deposition. The female does not die immediately, but instead hibernates and returns in the spring to care for the larvae during their early developmental stage. Some females may lay a second brood in the spring. The female and male cooperate in the construction of the nest in late August to early October. In the spring the male is ejected from the nest and dies shortly thereafter. The Earwigs' principal enemy is the tachinid fly, Bigonicheta spiniennis.
Hosts and Habitats
The European Earwig is an omnivore and feeds on other insects, plants, ripe fruit and garbage. It is particularly fond of clover, dahlias, zinnias, butterfly bush, hollyhock, lettuce, strawberry, celery, potatoes, roses, seedling beans and beets, and tender grass shoots and roots. It can also damage sweet corn by feeding on the silks. It is nocturnal, hiding during the day and foraging at night. In homes, it tends to hide in garden plants, shrubberies, along fences, in woodpiles, at the base of trees and behind loose boards on buildings and in the framework of walls. While chiefly an outdoor pest it is frequently brought inside with fruits and flowers.
New colonies tend to grow to a large population quickly and then gradually decline as resources dwindle or the home owner becomes aware of their presence. It is mostly disliked for its fearsome appearance, foul odor and habit of wallowing in kitchen refuse and wet mops. Although it does tend to destroy many household plants and kitchen produce it may have an unrecognized beneficial side effect as the majority of its diet is other small insects.
Major sources: University of Florida Department of Entomology. http://www.ifas.ufl.edu/~insect/veg/european_earwig.htm