Brushleg Mayfly vs Smoky Alderfly

Side-by-side species comparison

Attribute Brushleg Mayfly Smoky Alderfly
Scientific Name Isonychia bicolor Sialis fuliginosa
Order Ephemeroptera Megaloptera
Family Isonychiidae Sialidae
Size 12-18 mm 12-16 mm
Habitat Rivers & Streams Ponds & Lakes
Diet Omnivores Omnivores
Regions North America Europe
Conservation Least Concern Least Concern

Brushleg Mayfly

A large, fast-swimming mayfly with forelegs fringed with bristles for filter feeding. Nymphs inhabit swift riffles of large streams and rivers.

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Did You Know?

Unlike most mayflies, nymphs crawl out of water onto rocks to emerge as adults rather than hatching at the surface.

Smoky Alderfly

A European alderfly distinguished from S. lutaria by its preference for flowing water rather than still ponds. It has dark smoky wings and a blackish body.

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Did You Know?

This alderfly is a reliable indicator of clean running water and is one of the first species to disappear when streams become polluted.