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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
Baetis

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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Dark Gray-Winged Olive Duns

This common name refers to only one species. Click its scientific name to learn more.

Mayfly Species Baetis flavistriga

These are very rarely called Dark Gray-Winged Olive Duns.
This is one of the most widespread and abundant Baetis species, and it may produce fishable hatches under a variety of conditions.

This species is known in angling books by several old synonyms, including Baetis quebecensus, Baetis levitans, Baetis cingulatus, and Baetis phoebus, in addition to the correct name.
Dorsal view of a Male Baetis flavistriga (Baetidae) (BWO) Mayfly Nymph from the Dosewallips River in Washington
This nymph keys to Baetis assuming the villipore is present (hard to see in my photos or scope), and within that genus it tentatively keys to the flavistriga species complex, of which Baetis flavistriga itself is by far the most common in Washington state, so that's the most likely ID.

Dark Gray-Winged Olive Duns

Scientific Name
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