Alderflies, Dobsonflies & Fishflies (Order: Megaloptera)

A photograph of an adult Alderfly (Family Sialidae)

A photograph of an adult Alderfly (Family Sialidae).
Photograph by Fritz Geller-Grimm licensed under Creative Commons.

Originally the Alderflies and Dobsonflies were part of the Order Neuroptera. However, entomologists have now split the Order Neuroptera into three Orders:

Alderflies are brownish and rather stout, caddisfly-like insects, and are abundant near water in the early summer. There are only a handful of species in the UK and Europe.

Dobsonflies are well know in some parts of the world (North and South America) as the males have long mandibles (rather like tusks). Despite their appearance they are harmless.

Unlike the lacewings, antlions and snakeflies, the immature stages of dobsonflies and alderflies are always aquatic. They live under stones or submerged vegetation and feed on a variety of small aquatic organisms using biting jaws. Large species may require several years of growth to reach maturity.

Adults usually remain near water, although they are attracted to lights at night. In most species, the adults live only a few days and rarely feed.

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