Blue-Winged Olive vs Flat-headed Mayfly

Side-by-side species comparison

Attribute Blue-Winged Olive Flat-headed Mayfly
Scientific Name Baetis tricaudatus Epeorus assimilis
Order Ephemeroptera Ephemeroptera
Family Baetidae Heptageniidae
Size 5-9 mm 10-14 mm
Habitat Rivers & Streams Rivers & Streams
Diet Omnivores Herbivores
Regions North America Europe
Conservation Least Concern Least Concern

Blue-Winged Olive

A small olive-colored mayfly with distinctive bluish-gray wings, abundant in clean streams across North America. It produces multiple generations per year.

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Did You Know?

Blue-winged olives are among the few mayflies that hatch in winter, providing vital food for trout during cold months.

Flat-headed Mayfly

A stream-dwelling mayfly nymph with a flattened body for clinging to rocks in rapids.

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Did You Know?

Its flattened nymph shape allows it to live in the boundary layer of fast currents.