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Lateral view of a Female Hexagenia limbata (Ephemeridae) (Hex) Mayfly Dun from the Namekagon River in Wisconsin
Hex Mayflies
Hexagenia limbata

The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.

Case view of a Pycnopsyche guttifera (Limnephilidae) (Great Autumn Brown Sedge) Caddisfly Larva from the Yakima River in Washington
It's only barely visible in one of my pictures, but I confirmed under the microscope that this one has a prosternal horn and the antennae are mid-way between the eyes and front of the head capsule.

I'm calling this one Pycnopsyche, but it's a bit perplexing. It seems to key definitively to at least Couplet 8 of the Key to Genera of Limnephilidae Larvae. That narrows it down to three genera, and the case seems wrong for the other two. The case looks right for Pycnopsyche, and it fits one of the key characteristics: "Abdominal sternum II without chloride epithelium and abdominal segment IX with only single seta on each side of dorsal sclerite." However, the characteristic "metanotal sa1 sclerites not fused, although often contiguous" does not seem to fit well. Those sclerites sure look fused to me, although I can make out a thin groove in the touching halves in the anterior half under the microscope. Perhaps this is a regional variation.

The only species of Pycnopsyche documented in Washington state is Pycnopsyche guttifera, and the colors and markings around the head of this specimen seem to match very well a specimen of that species from Massachusetts on Bugguide. So I am placing it in that species for now.

Whatever species this is, I photographed another specimen of seemingly the same species from the same spot a couple months later.
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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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.

Taxon
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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
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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

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