Earwigs Introduction to the Dermaptera

Earwigs get bad press.  Because they have what look like pincers on their rear ends, people think they can pinch.  Because they wander around in houses, people think they are pests.  But earwigs cannot pinch and for the most part they are not pests.  Most earwigs live in natural ecosystems, minding their own business, which is to live in the leaf litter and scurry around finding food, avoiding predators and of course finding a mate and reproducing.

Earwigs are long and flattened with long antennae, chewing mouth parts and large pincer-like cerci at the back of the abdomen.  These are fixed and so cannot be used to hold prey.  Instead the cerci are used in mating or for carrying food items.  Most earwigs have two pairs of wings, where the front wings are short and hardened much like the forewings of beetles.  The membranous hind wings can be folded under the forewings for protection.  Some species are wingless.  Earwigs are usually from a half to five centimetres in length and dark brown to black in color.

Earwigs mate by grasping each other’s cerci and then the male puts the sperm packet in the female.  She can store the sperm for months before using it to fertilise her eggs.  First, she makes a burrow where she lays her eggs and then protects them from predators and cleans them to prevent fungal infections.  Earwigs are hemimetabolous insects with incomplete life cycles.  In other words, they do not go through a metamorphosis between larval and adult stages.  Earwigs hatch into tiny replicas of their parents.  The female may continue to look after them for a while but eventually they must disperse or she will eat them.

Earwigs live in cool, dark environments such as leaf litter on the forest floor.  They can also be found under rotting logs, rocks and the bark of trees.  They mostly eat plant material, living or dead while a few are predatory, killing and eating other insects.  Earwigs do their hunting at night, preferring to remain in sheltered environments during the day, when they are preyed upon by birds and other insectivores.

Earwigs belong to the insect order Dermaptera.  It is a small order containing an estimated 1000 living species worldwide.  The order is an old one, with fossils known from the Jurassic period, over 200 million years ago.  They may be primitive but what they do works for them and they will probably be around for millions of years more.

For more information:  http://www.ento.csiro.au/education/insects/dermaptera.html and http://bugguide.net/node/view/2709