Key to Australian Freshwater and Terrestrial Invertebrates

Phylum Arthropoda
Subphylum Hexapoda
Class Insecta
Order Dermaptera

Common name: earwigs

Overview

Dermaptera, or earwigs, are a distinctive group of insects with the body flattened and elongate, with heavily sclerotised, pincer-like cerci at the end of the abdomen. They range from 5�50 mm in length, have chewing (mandibulate) mouthparts, moderately long antennae, and are mostly dark brown to black in colour. Their forewings are short and hardened and the hindwings are membranous and, when not in use, are folded in a complex, fan-like way beneath the forewings. Many species are wingless (apterous). Females have straight cerci with an inward-pointing tip and males have curved cerci. Typically, earwigs are cryptic, nocturnal and require a humid micro-climate.

Distribution and diversity

Earwigs are distributed throughout Australia with the greatest diversity in the tropics and warm temperate areas. Worldwide there are around 1,800 species. The described Australian dermapteran fauna comprises 91 species in 38 genera and seven families; at least 30�40 further species await description. About 50% of Australian species are endemic.

Life cycle

Sperm transfer from male to female is direct. Earwigs mate end to end, often grasping each other's pincers. Females can store sperm for several months before fertilisation. A female will lay her eggs in natural crevices or in a burrow she has excavated in the soil. The female guards the eggs from predators and constantly turns and cleans them to prevent fungal diseases. The nymphs resemble small, pale adults and moult 4�5 times before maturity. They remain under the protection of their mother for a short time until they disperse.

Feeding

Probably most earwigs are omnivorous, eating a wide variety of plant and animal material. Species have been recorded as predators of a wide range of small, soft-bodied arthropods, feeding on adults, larvae and eggs. Others are mostly herbivorous on leafy herbs and vegetables, or detritivores, living on dead or decaying plant and animal matter and fungi. Earwigs grasp their food with their pincers and hold it while feeding.

Ecology

Earwigs are common over most of Australia and many species frequent backyard gardens and homes. Typically, they occur in dark, sheltered humid environments and can be found in crevices, leaf litter and under rocks, logs and the bark of trees. Globally, the majority of earwig species are found in tropical and subtropical latitudes, although in Australia, many endemic species are found in cool temperate forests. Earwigs are nocturnal and may be attracted to lights at night. The introduced European earwig, Forficula auricularia, is a commonly encountered pest in urban gardens and vegetable crops where it feeds on other insects, plants, fruit and garbage.