Earwigs are found in temperate regions to the tropics and subtropics. Of the approximately 1,800 species that exist worldwide, 28 species are found in the United States, and 6 species are found in the Great Lakes region. Those in the Great Lakes region are introduced from southern areas.
These nocturnal insects hide in cracks, crevices, under bark, and in debris during the day. If present in sufficient numbers, earwigs can be found hiding almost anywhere in the homes of humans.
Metamorphosis is simple with three stages of development. Temperature is important in controlling the rate of development which can range from 20 to 70 days. In the spring, the female will lay eggs. By late summer to early fall, the nymphs are fully grown. Adult earwigs overwinter.
Some species of Dermapterans have glands dorsally located on the third and fourth abdominal segments that contain a foul-smelling fluid. When provoked, the earwig will squirt this fluid for the sake of protection. They can squirt fluid 7 to 100 mm.
Although they have chewing mouthparts, earwigs are not known to bite when threatened or handled. If earwigs are handled, they can inflict a painful pinch with their cerci since their abdomens are quite flexible. The cerci are used for defense, prey capture, mating, and wing unfolding.
For those earwigs that have them, their wings are fully functional. In addition, earwigs are not known to crawl long distances. However, earwigs have spread rapidly thoughout parts of North America via hitchhiking, hiding in almost every item that potentially can be transported by humans.
Earwigs feed mainly on dead or decaying vegetable matter, and they will feed on living plants. They eat plant leaves, algae, fungi, sprouts and seedlings, flower petals, pollen, and corn silks. A few species are predators, eating other live insects and small invertebrates. The earwig will grasp its prey with its cerci, the pinchers at the end of its abdomen, and then bend so that the prey is within reach of its mouth. Earwigs will also scavenge dead insects and small invertebrates.
Dermapterans are contributors to biodegradation in that they are feeders of decaying organic matter.
Some earwigs may cause damage to flowers and vegetables, ornamental tress and shrubs. They are especially fond of corn. They have even been found in honey in beehives. When their populations increase, earwigs are found in homes, hiding in household items, foodstuffs, and most any other place, much to the disdain of humans.
Earwigs eliminate decaying organic materials from the environment.
The name "earwig" is derived from ancient tales that these insects will enter the ears of humans. It was once believed that earwigs would crawl into the ears of sleeping humans, then bore into the inner ears and brain, thereby causing insanity. This legend is not true.