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.
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This specimen resembled several others of around the same size and perhaps the same species, which were pretty common in my February sample from the upper Yakima. Unfortunately, I misplaced the specimen before I could get it under a microscope for a definitive ID.
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Mayfly Species Epeorus frisoni
This is a very uncommon species. The identification of all the specimens I've placed in this section is actually very uncertain, as they have proven incredibly difficult to identify. A professional entomologist collected more specimens from this stream, raised some nymphs, and did some genetic tests, and it's still uncertain. This reflects the ambiguity in the definitions and descriptions of many mayfly species.
Where & when
Preferred waters: Cold
Altitude: High
In 1 records from GBIF, adults of this species have been collected during August (100%).
Species Range
Specimens of the Mayfly Species Epeorus frisoni
2 Male Duns
I collected this male dun together with a female spinner, a female dun, and another male dun. I photographed this bedraggled one, larger than the other male, to show some of the greatest size variation within the species.
1 Female Dun
I collected this female dun together with a female spinner, a male dun, and a larger, damaged male dun.
1 Female Spinner
Start a Discussion of Epeorus frisoni
Mayfly Species Epeorus frisoni
Species Range
Resources
- NatureServe
- Integrated Taxonomic Information System
- Global Biodiversity Information Facility
- Described by Burks (1946)