Japanese Dobsonfly vs Common Alderfly

Side-by-side species comparison

Attribute Japanese Dobsonfly Common Alderfly
Scientific Name Protohermes grandis Sialis lutaria
Order Megaloptera Megaloptera
Family Corydalidae Sialidae
Size 40-60 mm body length 12-16 mm
Habitat Rivers & Streams Ponds & Lakes
Diet Predators Predators
Regions East Asia, Japan Europe, Asia
Conservation Least Concern Least Concern

Japanese Dobsonfly

A large aquatic insect known as 'hebi-tonbo' (snake dragonfly) in Japanese. The adult males have elongated, curved mandibles. Larvae called 'magotaro-mushi' are used as fishing bait.

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Did You Know?

Dobsonfly larvae are prized as live fishing bait in Japan and are collected from stream rocks by anglers targeting ayu (sweetfish).

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.