Earwig, Saint Helena giant

Labidura herculeana

phylum: Arthropoda

class: Insecta

order: Dermaptera

family: Labiduridae

status: Critically endangered, IUCN

range: Saint Helena

Description and biology

Of the 900 classified species of earwigs in the world, the Saint Helena giant earwig is the largest, with an average body length of 1.4 to 2.1 inches (3.6 to 5.3 centimeters). Males are larger than females. The horny, forceplike pincers extending from the rear of the body measure between 0.6 and 0.9 inch (1.5 and 2.3 centimeters). Males use their pincers to battle each other over the right to mate with a female. The pincers in females are shorter but more serrated. Both males and females have black bodies and reddish legs. This earwig species is wingless.

The largest Saint Helena giant earwig ever collected is housed in a Belgium museum. It is a male with a total body and pincher length of more than 3 inches (7.6 centimeters).

Mating between males and females seems to take place between December and February.

Habitat and current distribution

The Saint Helena giant earwig is found only on the island of Saint Helena, a British dependency (territory) located in the southern Atlantic Ocean about 1,200 miles (1,931 kilometers) off the southwest coast of Africa. On Saint Helena, the earwig is restricted to Horse Point Plain in the extreme northeast portion of the island.

Horse Point Plain is dry and barren. Small bushes and tufts of grass are the main types of vegetation in the area. The earwig prefers to live under stones or in the soil near burrows that it uses as escape routes. During the summer rainy season, the insect is active. When the dry season begins, the earwig seeks shelter underground.

History and conservation measures

The Saint Helena giant earwig was discovered on Saint Helena in 1789. Until 1965, the insect was considered quite common on the island.

However, recent searches on Saint Helena have failed to find a single earwig. The reason is that much of its habitat has been altered or destroyed. Soil erosion is widespread because native plants have been cleared from large areas. Surface rocks in these areas have been removed for use in building human dwellings. As a result, the earwig has been left with an open, barren habitat that affords little protection.

In addition to the loss of its habitat, the Saint Helena giant earwig is further threatened by a number of introduced predators, particularly mice and centipedes.

Unless conservation measures are taken soon, the critically endangered Saint Helena giant earwig faces the real possibility of extinction.

DID YOU KNOW?

Further attention was brought to the plight of the St. Helena giant earwig on January 4, 1982, when the Philatelic (stamp collecting) Bureau of the St. Helena Post Office issued a commemorative postage stamp depicting the insect. The stamp carried a postage price of £1 (one pound British sterling).