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Snakeflies are insects in the family Raphidiidae, in the order Neuroptera, which also contains the closely related alderflies (Sialidae) and dobsonflies (Corydalidae). There are not many species of snakeflies. The approximately 20 species that occur in North America are all western in their distributions.

Snakeflies have a complete metamorphosis, with four stages in their life history: egg, larva, pupa, and adult. The larvae of snakeflies are terrestrial, usually occurring under loose bark of trees, or sometimes in litter on the forestfloor. Snakefly larvae are predators, especially of aphids, caterpillars, and the larvae of wood-boring beetles.

The adult stage of snakeflies is a weakly flying animal. Adult snakeflies are also predators of other insects, although they are rather short-lived, and their biological purpose is focused on breeding. Their eggs are usually laid in crevices in the bark of trees.

Like other insects in the order Neuroptera, adult snakeflies have long, transparent wings, with a fine venation network. The common name of the snakeflies derives from the superficially snaky appearance that is suggested by the unusually long, necklike appearance of the front of their thorax (that is, the prothorax), and their rather long, tapering head.

Agulla unicolor is a relatively widespread, dark-brown species of snakefly that occurs in montane forests of western North America. Raphidia bicolor is another western species, which occurs in apple orchards and can be a valuable predator of the codling moth (Carpocapsa pomonella), an important pest.

Bill Freedman

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