Mountain Prosimulium vs Eastern Weighted Casemaker

Side-by-side species comparison

Attribute Mountain Prosimulium Eastern Weighted Casemaker
Scientific Name Prosimulium mixtum Goera stylata
Order Diptera Trichoptera
Family Simuliidae Goeridae
Size 2-4 mm 8-12 mm
Habitat Mountains Rivers & Streams
Diet Omnivores Omnivores
Regions North America Europe
Conservation Least Concern Least Concern

Mountain Prosimulium

An early-season black fly of cold mountain streams in North America. Larvae develop in small headwater streams during late winter and early spring.

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Did You Know?

Adults emerge so early in spring that they are often the first biting flies encountered by hikers each year.

Eastern Weighted Casemaker

A caddisfly of clean European streams that builds mineral cases with large lateral ballast stones. Larvae scrape algae from rock surfaces in moderate current.

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Did You Know?

The lateral ballast stones are so precisely placed they appear to be glued on by hand.