Large Alderfly vs Western Dobsonfly

Side-by-side species comparison

Attribute Large Alderfly Western Dobsonfly
Scientific Name Sialis nigripes Neohermes californicus
Order Megaloptera Megaloptera
Family Sialidae Corydalidae
Size 15-20 mm 50-70 mm wingspan
Habitat Rivers & Streams Mountains
Diet Herbivores Predators
Regions North America Western North America
Conservation Least Concern Least Concern

Large Alderfly

A relatively large alderfly with dark wings and black legs found near rivers in eastern North America. Adults rest on streamside vegetation during the day.

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Did You Know?

Alderfly larvae breathe through feathery gills along their abdomen and a single long tail filament that acts as an additional gill.

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.