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Lateral view of a Male Baetis (Baetidae) (Blue-Winged Olive) Mayfly Dun from Mystery Creek #43 in New York
Blue-winged Olives

Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.

27" brown trout, my largest ever. It was the sub-dominant fish in its pool. After this, I hooked the bigger one, but I couldn't land it.
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Mayfly Genus Acerpenna (Tiny Blue-Winged Olives)

See Acerpenna pygmaea for details. It is the only species known to be of even minor importance to anglers and was previously known as Baetis pygmaeus.

Where & when

In 38 records from GBIF, adults of this genus have been collected during July (37%), June (26%), May (18%), April (8%), September (5%), and August (5%).

In 52 records from GBIF, this genus has been collected at elevations ranging from 3 to 4692 ft, with an average (median) of 1713 ft.

Genus Range

Specimens of the Mayfly Genus Acerpenna

2 Male Spinners
2 Female Spinners
1 Nymph

Start a Discussion of Acerpenna

Mayfly Genus Acerpenna (Tiny Blue-Winged Olives)

3 species (Acerpenna macdunnoughi, Acerpenna sulfurosa, and Acerpenna thermophilos) aren't included.
Genus Range
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