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.

Stream photos

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Epeorus albertae (Pink Lady) Mayfly Nymph Epeorus albertae (Pink Lady) Mayfly Nymph

Dorsal view of a Epeorus albertae (Heptageniidae) (Pink Lady) Mayfly Nymph from the East Fork Issaquah Creek in Washington

This specimen keys to the Epeorus albertae group of species. Of the five species in that group, the two known in Washington state are Epeorus albertae and Epeorus dulciana. Of the two, albertae has been collected in vastly more locations in Washington than dulciana, suggesting it is far more common. On that basis alone I'm tentatively putting this nymph in albertae, with the large caveat that there's no real information to rule out dulciana.

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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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Puzzled on this mayfly, not even confident on family

Male Rhithrogena hageni (Western Black Quill) Mayfly Spinner

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Lateral view of a Male Rhithrogena hageni (Heptageniidae) (Western Black Quill) Mayfly Spinner from the Ruby River in Montana

Although I could not find the preserved specimen to examine under my good new microscope, I'm tentatively calling it one Rhithrogena hageni, based on apparent similarity to this specimen, which I was able to positively ID.

The relative angle of the penes is a bit shallower in this specimen, but I photographed another specimen from the same collecting trip (and I think even the same swarm, although I don't recall for sure) as the other one, and it had the shallower angle seen on this specimen. I'm guessing it's just variation within the species.

Collected July 7, 2019 from the Ruby River in Montana

Added by Troutnut on July 18, 2019

Collected July 7, 2019 from the Ruby River in Montana and added by Troutnut on July 18, 2019

Troutnut

Administrator
Bellevue, WA

Posts: 2758

Troutnut on Jul 22, 2019July 22nd, 2019, 8:11 pm EDT

This seems to be some sort of Heptageniid, based on the two tails and five segments on the hind tarsus. Following the key in Merritt & Cummins seems to lead to Rhithrogena, but it doesn't fit a characteristic described in Needham's Biology of Mayflies for that genus: "Tibia of hind leg in both sexes about 1/4 length of femur."

Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

Millcreek
Healdsburg, CA

Posts: 344

Millcreek on Jul 23, 2019July 23rd, 2019, 10:34 am EDT

For what it's worth, this seems to be Heptageniidae and Rhithrogena based on the wings and penes. Also, if you take a look at Bugguide the photos there don't show the hind tibia being 1/4 the length of the femur.

https://bugguide.net/node/view/50753/bgimage?from=0

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