The members of the insect order Mecoptera are commonly known as scorpionflies, although only the males of one family actually have an upturned tip to the abdomen that superficially resembles a scorpion's tail, but is harmless. Most scorpionflies are small insects with long thin legs and wings. Their most prominent feature are elongated mouthparts that resemble a weevil's snout or Jimmy Durante's nose. They are among the most primitive of the holometabolous insects, that is, insects with a complete life cycle that goes through egg, larval, pupal and adult stages. They first appear in the fossil record back in the Permian, some 250 million years ago. More fossil species are known that living ones and there are about 500 described species worldwide.
Most scorpionflies are herbivorous and have simple chewing mouthparts. A few males catch other insects or even spiders. Some scorpionflies are able to walk safely over a spider's web without alerting the spider to their presence. Most live in moist, cool habitats, usually around swamps or small streams.
Scorpionflies have interesting sex lives. The males attract the females with pheromones and then offer them 'nuptial gifts', usually a bit of food. The male pierces the food item and then offers it to a female. He seizes the female and offers her the food to eat while he mates with her. Then he may take the food back to eat himself or offer it to another female. Sometimes males steal the nuptial gifts from each other in order to attract females. The males also become aggressive and will try to drive off a mating male so they can muscle in. However the males have gripping structures on the ends of their abdomens and so can be hard to dislodge before sperm transfer takes place.
The females lay eggs in batches on the ground or in crevices. They hatch after a week or so and then forage until they are large enough to pupate. The larvae feed on pollen, nectar and flowers.
There are two interesting groups of scorpionflies that differ from the norm. The first are known as snow scorpionflies. They live at high altitudes in the Northern Hemisphere and feed on mosses. They have vestigial wings and cannot fly. They got their name because they are often found on the snow in winter. The males use their bristle-like wings to hang on to the females during mating.
The other group are known as the hanging scorpionflies because they hang from vegetation by their long forelegs and capture prey with the hind legs. They look a lot like crane flies but they are not true flies because they have four wings and not just two.
Because scorpionflies do not bite or sting humans and do not eat any crops, they are seldom noticed and are of no economic importance.