Key to Australian Freshwater and Terrestrial Invertebrates

Phylum Arthropoda
Subphylum Hexapoda
Class Insecta
Order Mecoptera

Common names: scorpion flies, hanging flies

Overview

Mecoptera, or scorpion flies, are slender, winged insects with long, thin legs and strong claws. Superficially they resemble large mosquitoes or crane flies (Diptera). Their common name derives from the fact that the abdomen of some males bear genitalia that resemble the stinging tail of a scorpion; often they fly with it raised. Adults generally have long, segmented antennae, large eyes, chewing (madibulate) mouthparts located at the tip of beak-like extension of the head, and two pairs of membranous wings that are similar in size. Very few species are wingless (apterous) or short winged (brachypterous). Males have claspers at the tip of the abdomen; these are used to hold onto the female during mating. Scorpion flies can have a wingspan up to 50 mm. The larvae appear similar to caterpillars or grubs and have three pairs of short legs and well-developed mandibles.

Distribution and diversity

Typically, Mecoptera are found in cool, moist environments. In Australia, scorpion flies are common around mountain and coastal regions, although some species occur further inland. About 600 species have been described worldwide. Thirty species in 12 (mostly endemic) genera from five families are recorded from Australia.

Life cycle

One family (Bittacidae), are known for their elaborate mating rituals. The female is first attracted to the males by a pheromone. She then chooses mates and time spent copulating based on the quality of prey (e.g. caterpillars, bugs, flies) offered by various males and to be eaten during copulation. In other families the male vibrates his wings and/or waves his antennae to attract a female before securing her abdomen with his claspers. Sometimes the male produces a thick pellet of saliva on which the female feeds during copulation. Females deposit eggs in moist soil, moss or leaf litter; some species are aquatic and place their eggs in the water. Larvae develop through three instars, taking from 1�3 months each before pupating for up to several months within a chamber in the soil.

Feeding

Larvae feed on dead and decaying arthropod and plant matter in soil and leaf litter. Some species are cannibalistic, the larger individuals feeding on smaller ones. Adult Mecoptera are typically omnivorous, preying on small insects and feeding on petals, nectar, fruits, pollen, leaves and mosses.

Ecology

Mecoptera are usually found in moist habitats or adjacent to open water, although some species are found in drier areas. Adults are active during the day and may be seen hanging from low vegetation waiting to catch prey with their hind legs or flying among flowering plants, preying on flies, bees, caterpillars and other insect larvae. In Tasmania, a wingless species (Apteropanorpa tasmanica) can be found on snow. The larvae typically live in the soil, leaf litter or among moss in damp, shaded areas.