Earwigs have smooth, slender, flattened bodies and beadlike antennae. Where other insects have wings, most earwigs have two leathery, budlike covers (tergites). Some species fold wings under these covers; others lack wings, tergites, or both. The pair of large pincers at the abdomen tip are modified cerci (SUR-sigh; singular cercus, SUR-kuss) and function to repel predators. (They are anatomical equivalents to the two filaments at the end of a cricket’s body, which function like antennae.) The shape and size of male earwigs’ pincers help identify species. Females’ pincers don’t vary so much.
The European earwig (Forficula auricularia) is one of our most common earwigs. It is reddish brown, has functioning wings, and can fly. The teeth at the base of its cerci distinguish it from other earwigs. The native ring-legged earwig (Euborellia annulipes) is dark brown, with light yellow legs with dark, ringlike marks. US members of this species lack wings and budlike tergites.
Length (not counting cerci): about ¼ to 1¼ inches (varies with species).
Habitat and Conservation
Earwigs prefer cool, moist, dark places. They hide under leaves, rocks, bark, stacked lumber, bundles of newspaper, and so on. When you overturn a log or rock, any earwigs you uncover will scurry to another place of refuge. Some earwigs have wings and are attracted to lights at night. Of the nearly 30 species of earwigs in North America, about half were introduced from elsewhere. The European earwig is today found nearly worldwide and is one of our most common species.
Different earwig species have slightly different diets, but most are scavengers. The European earwig is a scavenger, preying on small invertebrates and sometimes chewing plants, living or dead. The native ring-legged earwig is also a predator, devouring slugs, aphids, caterpillars, termites, and other invertebrates. It also eats some plant material, but it rarely chews on living plants.
Gardeners worry about them, and earwigs do sometimes chew leaves — but earwigs also devour several types of aphids and other pests that are much worse than they. Before waging war against earwigs, make sure they are the true culprits. When earwigs enter homes, they do not cause damage. If you don’t care to see them, caulk and seal cracks around your home, weatherstrip doors, keep decaying plant matter away from your house, clean up your clutter, and reduce moisture in your basement.
Earwigs, like true bugs, grasshoppers, and dragonflies, undergo incomplete metamorphosis. Unlike butterflies, bees, and beetles, they do not have a pupal stage between two drastically different body forms. Instead, from egg to nymph to winged adult, their development is gradual over 4–6 molts, and nymphs have the same basic body plan as adults. Earwigs live for about a year. A mother earwig carefully tends her nest of eggs, cleaning and defending them. She even feeds the young after they hatch.
For ages, earwigs have suffered from bad press. Their name has hardly changed since the 12th century Old English ēare wicga (ear insect) — and the superstitious, completely incorrect belief that they habitually creep into sleeping humans’ ears is just as ancient. Earwigs cannot harm people.
Earwigs clean the natural world, bit by bit, of decaying plant and animal matter. They also help control populations of the insects and other small animals they eat. And when they prune plants with their chewing, it naturally encourages strains with vigorous growth.