Article 121 : Earwigs

EARWIGS

by Lisa Marie Gee


Earwigs first showed up in fossil records about 208 million years ago. They are most common in the tropics but there are about 23 species in the U.S. with 12 of those introduced from other countries. The European earwig, Forficula auricularia L., is in much of the U.S. and was introduced into North America in the early 1900’s.

Its overall length is usually between ¼-5/8th inch, the largest being an Australian Giant Earwig which can grow to 2 inches. Earwigs have a flattened dark brown body. The head is reddish with 2 small compound eyes and 2 long thin antennae. The mouth parts are for chewing and include the labrum, labium, maxillae and mandible. The brain is mostly clusters of neurons that interpret sensory information.

The thorax has 3 pairs of legs and 2 pairs of wings. The legs are long for running. Despite wings earwigs are not good fliers and flying is rare. The short fore-wings cover the hind wings. The hind wings are large, semi circular and folded first lengthwise then crosswise!

The earwig’s abdomen contains the nervous, digestive, circulatory and reproductive systems. Some species do have glands that can shoot off an offensive fluid up to 4 inches if provoked. The pinchers are also at the end of the abdomen section and they use these to help fold their hind wings, defend themselves and capture prey. The female’s pinchers are relatively straight where the male’s are shaped like calipers.

Earwigs mate in the fall and both male and female stay together in the nest through the fall and early winter. The nest is about 1 inch deep under debris, in crevices or in soil. In mid-winter to early spring the male leaves the nest. The female will lay between 50-80 eggs and can have 1-2 broods in a season. The eggs hatch in about 7 days and the nymphs’ first meal is their egg case. An unusual characteristic of the female earwig is that she takes care of her young. If the eggs become dispersed, she will move them back together. She keeps the eggs free of parasites and fungi by licking them clean. She will deliver the nymphs food until they can take care of themselves which is generally after the 2nd molt. If they don’t leave the nest the mother may eat them! Nymphs look like the adults but smaller, wingless and pale. They molt 4-5 times and with each molt the wings and antennae get longer and are mature in about 50 days. This life cycle is incomplete metamorphosis and the earwig lives about a year after hatching.

Earwigs are omnivorous, eating plant material, fungi, algae, moss, pollen and flowers or they are scavengers on dead and dying vegetation. They will occasionally prey on small insects like aphids and mites. They may cause minimal damage to plants but can be beneficial as recyclers of decaying material and as predators.

Ear wigs are nocturnal. They live in dark, moist places so look under stones, boards, mulch, dead leaves, logs, flowerpots and rotting wood if you wish to see them. They may enter your house accidentally or during prolonged heat and drought. Once inside they will have to eat and your houseplants and food might be a target. If in the house you can gently sweep them up and take them outside. Don’t crush them as they will have an obnoxious odor.

To manage earwigs outside eliminate damp/moist conditions. Eliminate boards, tree holes, decaying bark, decaying vegetable matter, piles of leaves or grass clippings. There are grooved board traps that can be placed but should be tended daily by emptying them. There are also exterior perimeter sprays but make sure you read and follow the directions. Earwigs for the most part do not bother humans so if possible, try to coexist with them even if they look ominous with those pinchers!

© Copyright 2019 All Rights Reserved

Last updated October 16, 2019