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.

I spent more than an hour casting to several rising trout in this pool and caught only two. Its clear water and tricky currents harbor dozens of free-rising, usually very hard-to-catch fish.

From Enfield Creek in New York

Stream photos

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Perlodidae (Springflies and Yellow Stones) Stonefly Nymph Perlodidae (Springflies and Yellow Stones) Stonefly Nymph

Artistic view of a Perlodidae (Springflies and Yellow Stones) Stonefly Nymph from the Yakima River in Washington

This one seems to lead to Couplet 35 of the Key to Genera of Perlodidae Nymphs and the genus Isoperla, but I'm skeptical that's correct based on the general look. I need to get it under the microscope to review several choices in the key, and it'll probably end up a different Perlodidae.

11 Recently Added Photos

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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Sweltsa?

Female Sweltsa (Sallfly) Stonefly Adult

8 Pictures

Lateral view of a Female Sweltsa (Chloroperlidae) (Sallfly) Stonefly Adult from the Madison River in Montana

These stoneflies--abundant during midday--seemed at first to be flying around with plain yellow bodies, but on closer inspection turn out to have striking, fiery red abdomens.

Collected June 29, 2019 from the Madison River in Montana

Added by Troutnut on July 17, 2019

Collected June 29, 2019 from the Madison River in Montana and added by Troutnut on July 17, 2019

Taxon

Site Editor
Plano, TX

Posts: 1311

Taxon on Jul 17, 2019July 17th, 2019

Hi Jason-

My guess would be genus Sweltsa, of which I believe there to be ~8 species in MT. It looks pretty similar to a (mostly) dorsal view of Sweltsa townsesi, which is pictured in American Stoneflies: A Photographic Guide to the Plecoptera by Bill B. Stark, et. al. However, I believe that species is only present in the Northern Sierra Nevada Mountains of CA and NV.

Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com

Troutnut

Administrator
Bellevue, WA

Posts: 2758

Troutnut on Jul 17, 2019July 17th, 2019, 8:03 pm EDT

Thanks Roger. I'll put it there for now, along with another specimen of similar but not identical coloration and a few mm greater length.

FYI, today and tomorrow I'm adding quite a few more specimens from this year's Montana trip and would definitely appreciate any ID thoughts if you have time. I'll message Dave about the caddis soon, too.

Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

Blue-winged OlivesBaetis

Troutnut Forum › Specimen Discussion › Sweltsa?