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Description & Statistics
Mecoptera, or "scorpion flies,"occur in shaded habitats and areas of dense vegetation where the soil is moist. The larvae are eruciform and are found on or in the soil in rather damp places. Adults and larvae of many species are predaceous, but some species are also saprophagous. Larvae of Panorpa feed on dead or dying insects and rarely if ever on active living forms. Bittacus is essentially predaceous on such insects and other small animals that occur in or on the moist soil (Clausen 1940/1962). They are thought to have little importance to biological control.
In the order Mecoptera there were 25 genera and more than 409 species known as of 2000. They are mainly tropical and temperate insects. Diagnostic characters include a head that is prolonged downward in the shape of a beak or rostrum; the antennae are long and filiform; and the fore and hind wings are of almost equal size. They have three ocelli, which are quite large and well developed; the legs are long, lean, and the body is generally small.
Mecoptera are primarily predators or consumers of dead organisms, early ones might have played an important role before the evolution of other insects in pollinating extinct gymnosperms.
All species are small to medium sized with slender, elongated, bodies. They have simple mouthparts, with long mandibles and fleshy palps, which resemble those of the more primitive true flies. Like many other insects, they possess compound eyes on the side of the head, and three ocelli on the top. Most species feed on vegetation in moist environments; in hotter climates, they may therefore be active only for short periods of the year.
The wings are narrow, with many cross-veins, and they resemble those of primitive insects such as mayflies. A few genera, however, have reduced wings, or have lost them altogether. The abdomen is cylindrical, and typically curves upwards in the male, superficially resembling the tail of a scorpion.
The female lays the eggs in moist areas, and then the eggs absorb water and increase in size after deposition. In species that live in hot conditions, the eggs may not hatch for several months, the larvae only emerging when the dry season has finished. More typically, however, they hatch after a relatively short period of time.
The larvae are resemble caterpillars, with short, clawed, true legs, and a number of abdominal prolegs. They have a sclerotised head with compound eyes and mandibulate mouthparts. The tenth abdominal segment bears either a suction disc, or, less commonly, a pair of hooks. They generally eat vegetation or scavenge for dead insects, although some predatory larvae are known.
The larvae crawl into the soil or decaying wood to pupate, and o not spin a cocoon. The pupae are exarate, with the limbs free of the body, and are they able to move their mandibles, but are otherwise they are entirely non-motile. In drier habitats, they may remain for a few months in diapause, before emerging as adults once the conditions are optimum.
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