Dermaptera is the scientific order encompassing a group of insects commonly recognized as earwigs. These insects are found across all continents except Antarctica, making them a widespread presence in various environments. They are distinguished primarily by a pair of prominent, forceps-like appendages located at the rear of their abdomen. This order comprises approximately 2,000 known species, making it one of the smaller insect orders.
Defining Physical Features
Earwigs have an elongated and flattened body. Their heads are prognathous, meaning their mouthparts are directed forward, and they feature segmented antennae that can have 10 to 16 segments. Most species have chewing mouthparts, adapted for their varied diet.
Earwigs have wings, though many species rarely fly or are wingless. When present, the forewings are short, leathery plates called tegmina, which serve to protect the larger, membranous hindwings. These hindwings are semicircular and intricately folded like a fan beneath the tegmina when not in use. Their most recognizable feature is the pair of unsegmented cerci, or pincers, at the end of their abdomen. These cerci exhibit sexual dimorphism; males typically have larger, more curved pincers, while females possess straighter, smaller ones. Earwigs vary in size, generally ranging from 5 to 50 millimeters in length.
The Truth About the Earwig Name
The common name “earwig” stems from an old European superstition suggesting these insects crawl into human ears to lay eggs or burrow into the brain. This widespread belief is entirely unfounded and lacks scientific basis. Earwigs are not interested in entering human ears, and while isolated incidents of insects entering ears can occur, it is not a characteristic behavior of earwigs.
The name’s true origin likely relates to the appearance of their hindwings, which, when unfolded, can resemble the shape of a human ear. Another possibility is its derivation from Old English words, “eare” meaning ear and “wicga” meaning insect, collectively referring to an “ear creature” or “ear wiggler.” The cerci, their prominent pincers, serve several functions for the insect itself. They are used for defense against predators, for grasping prey, and play a role in courtship rituals.
Ecological Role and Behavior
Earwigs are primarily nocturnal insects, seeking shelter in dark, moist environments. These preferred habitats include areas under rocks, within leaf litter, beneath loose tree bark, or in garden soil and compost piles. Their tendency to hide in such places often leads to encounters with humans when these sheltered areas are disturbed.
These insects are omnivorous. They consume a wide array of organic matter, including decaying plant material and fungi, contributing to decomposition processes in ecosystems. Earwigs also feed on living plants, sometimes causing damage to seedlings, flowers, fruits, and vegetables, which can make them garden pests. Conversely, many earwig species are beneficial predators, actively hunting and consuming other small insects such as aphids, caterpillars, mites, and even slug eggs. This dual feeding habit highlights their complex role in garden ecosystems, acting as both occasional nuisances and natural pest controllers.
Reproduction and Maternal Instincts
Earwigs undergo incomplete metamorphosis, with stages of egg, nymph, and adult. Mating typically occurs in the fall and early winter months. Following mating, the female earwig excavates a small underground chamber or “cell” where she lays her eggs.
A female earwig lays multiple clutches of eggs, with each clutch typically containing 20 to 80 smooth, oval, white or cream-colored eggs. A remarkable aspect of Dermaptera biology is the female’s sophisticated maternal care, which is uncommon among non-social insects. The mother guards her eggs diligently, protecting them from predators and even her own mate. She meticulously cleans the eggs by licking them, a behavior thought to prevent fungal growth that could harm the developing embryos. After the eggs hatch, the mother continues to care for the young nymphs, providing protection and sometimes even food, until they have undergone their first or second molt and are ready to disperse and forage independently.