Insects in the Order Megaloptera are among the most primitive insects that show complete metamorphosis (i.e. whose development stages are egg, larva, pupa and adult). The Order contains about 300 species.

Originally the Alderflies, Dobsonflies & Fishflies were part of the Order Neuroptera. However, entomologists have now put them in their own Order called Megaloptera.

Alderflies are brownish and rather stout insects. 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.

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.

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.

Other names for (or types of) Megaloptera include:

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