Western Dobsonfly vs Common Alderfly

Side-by-side species comparison

Attribute Western Dobsonfly Common Alderfly
Scientific Name Neohermes californicus Sialis lutaria
Order Megaloptera Megaloptera
Family Corydalidae Sialidae
Size 50-70 mm wingspan 12-16 mm
Habitat Mountains Ponds & Lakes
Diet Predators Predators
Regions Western North America Europe, Asia
Conservation Least Concern Least Concern

Western Dobsonfly

A large dobsonfly of western North American streams, smaller than its eastern relative. Larvae are top predators under rocks in cool mountain streams.

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Did You Know?

Unlike eastern dobsonflies, males of this species lack the enlarged mandibles.

Common Alderfly

A dark smoky-winged insect commonly found near still or slow-moving waters across Europe. Its aquatic larvae are predators in lake and pond sediments.

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Did You Know?

Alderfly females lay hundreds of eggs in neat rows on vegetation overhanging water, and the larvae drop into the water upon hatching.