Insects and their Allies  

Mecoptera: scorpion flies

Scorpion flies are small to medium sized insects with a wing span up to 50 millimetres in some species. Their name is derived from the fact that the abdomens of some male species have genitalia that resemble the stinging tail of a scorpion and will often fly with it raised. Scorpion flies are often mistaken for giant mosquitoes or crane flies (Diptera) but can be distinguished by the following features:

Chorista species
Chorista species (CHORISTIDAE)

  • 2 pairs of membranous wings of almost equal size. Some species are wingless
  • Mandibulate mouthparts at the end of a beak-like projection on the head
  • Very long spindly legs with strong claws

The larvae of scorpion flies appear similar to caterpillars with short legs, but do not possess prolegs and have well developed mandibles.

Chorista species (above) prefer to live close to water and are apparently mainly herbivorous. Adults lay their eggs in pockets in damp situations. The larvae are almost completely smooth and live in the leaf litter and low vegetation. They pupate in earthen cells in the soil.

Life Cycle
The life cycle of Scorpion flies is varied but in most cases the male attracts the female with pheromones and offers her an insect meal he has previously captured. It is thought this food is required by the female to assist with egg development. Eggs are usually deposited in the soil or moist leaf litter, while some species are aquatic and eggs are placed in the water. Larvae develop through 3 instars lasting approximately one month each before pupating for up to several months within a chamber in the soil. Adults may hatch in spring or autumn depending on the species.

Scorpion flies primarily feed on nectar, pollen, fruit and mosses although males will also feed on many soft-bodied insects. Some species fly among flowering plants preying on flies, bees, caterpillars and other insect larvae. The diet of scorpion fly larvae is varied and may include dead and dying insects or various plant materials.

Scorpion flies prefer cool, moist environments and are common around mountain and coastal regions of the country, although some species are found in the more marshy areas of inland Australia. Adults can often be seen hanging from low vegetation waiting for a chance to capture passing prey with their hind legs.