Earwig

Earwigs are a diverse group of insects belonging to the order Dermaptera. This scientific name comes from Greek words meaning "skin wings." This name describes their unique wing structure. They possess short, leathery forewings that act as protective covers. Underneath these covers, they hide delicate, membranous hindwings. There are approximately 2,000 known species divided into 12 different families. While they are a relatively small insect order, they are found on every continent except Antarctica.

The physical structure of an earwig is built for life in tight spaces. Most species have elongated, flattened bodies. This shape allows them to squeeze into narrow crevices like tree bark or soil. Their most famous feature is a pair of forceps-like pincers on the abdomen called cerci. These cerci serve many vital functions. Earwigs use them to capture prey and to defend themselves against predators. They also use the pincers to help fold their complex hindwings.

Wing mechanics in earwigs are highly specialized. The hindwing is a very thin membrane that expands like a fan. It radiates from a single point and is folded tightly under the short forewings, known as tegmina. These tegmina are sclerotized, meaning they are hardened, to protect the wings. The process of folding these wings is unique among insects. It actually requires the use of the cerci to manage the intricate venation and folding pattern.

Earwigs undergo a developmental process called incomplete metamorphosis, or hemimetabolous development. This means they do not have a pupal stage like butterflies. Instead, they grow through a series of stages called instars. A young earwig will typically undergo five molts in its first year before reaching adulthood. During these stages, sexual dimorphism begins to appear. This is when males and females start to look different. For example, male earwigs generally develop more curved pincers than females.

One of the most remarkable aspects of earwig biology is their maternal care. This behavior is quite uncommon among the insect world. After mating in the autumn, the female lays between 20 and 80 pearly white, oval-shaped eggs. She does not leave them. Instead, she stays to protect the eggs from predators and keeps them warm. She also performs a continuous cleaning ritual to protect the eggs from fungi. She will continue to care for her offspring, called nymphs, until they complete their second molt.

The history of the Dermaptera order stretches back millions of years. Living earwigs belong to the suborder Neodermaptera, which first appeared during the Cretaceous period. Fossil evidence also shows older groups existed in the past. Some fossils are placed in the extinct suborder Archidermaptera, which dates to the Late Triassic. Other fossils belong to the Eodermaptera, which date to the Middle Jurassic. This shows that the basic earwig body plan has been successful for a very long time.

Earwigs are found in many different environments and sizes. The Australian giant earwig, Titanolabis colossea, is a massive species reaching about 35 millimeters. There was once a species on Saint Helena that reached a similar size before being declared extinct in 2014. In North America, about 25 species exist. The common earwig, Forficula auricularia, was introduced from Europe in 1907. While most earwigs are nocturnal scavengers, some can be quite aggressive. Some species, like Doru taeniatum, can even squirt a foul-smelling yellow liquid from scent glands to scare away threats.

Ecologically, earwigs play various roles in their habitats. Most are omnivores or scavengers that eat plants, fruit, and other insects. However, some species are specialized parasites. Certain groups, such as those in the suborders Arixeniina and Hemimerina, are wingless and blind. These specific earwigs live as parasites on other animals. This shows how much the order has adapted to different ways of living. Whether they are hiding in woodland debris or living in caves, earwigs are a highly adaptable group of insects.