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Artistic view of a Male Pteronarcys californica (Pteronarcyidae) (Giant Salmonfly) Stonefly Adult from the Gallatin River in Montana
Salmonflies
Pteronarcys californica

The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.

Dorsal view of a Setvena wahkeena (Perlodidae) (Wahkeena Springfly) Stonefly Nymph from Mystery Creek #199 in Washington
As far as I can tell, this species has only previously been reported from one site in Oregon along the Columbia gorge. However, the key characteristics are fairly unmistakable in all except for one minor detail:
— 4 small yellow spots on frons visible in photos
— Narrow occipital spinule row curves forward (but doesn’t quite meet on stem of ecdysial suture, as it's supposed to in this species)
— Short spinules on anterior margin of front legs
— Short rposterior row of blunt spinules on abdominal tergae, rather than elongated spinules dorsally
I caught several of these mature nymphs in the fishless, tiny headwaters of a creek high in the Wenatchee Mountains.
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.
Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

Some winter nymph collecting on the Yakima

Some winter nymph collecting on the Yakima

By Troutnut on February 17th, 2023
I was in the vicinity of the upper Yakima River this weekend, but not in a good spot to try any winter fishing. So I brought my bug collecting supplies and sampled a bunch of nymphs and larvae, aiming to get some more good images to illustrate the new taxonomic keys. I was hoping to find a nice intact Skwala stonefly nymph to add to the beat-up one on the site already, a Nemouridae stonefly nymph for some proper anatomical close-ups, ditto for Capniidae or Leuctridae, and a variety of cased caddis larvae because I just don't have very many recent pictures of those with my best equipment. I met all these goals with the exception of Capniidae and Leuctridae, which will have to wait for another trip. On the way home I also stuck the net in a creek slightly closer to home and turned up some Epeorus nymphs, mostly Epeorus grandis which I didn't bother to photograph, but one from the Epeorus albertae group.

The unexpected highlight of the trip did not become apparent until after some time at the microscope. It seems I collected a several nymphs of Ephemerella mucronata, an obscure relative of the Hendrickson and Sulphur hatches, which has a holarctic distribution but has not previously been documented any closer to Washington than Montana and Alberta. However, there is a chance they belong to some other species not well-described as nymphs yet. I hope to collect more mature specimens and rear a few into adults to get a more definitive species ID.

Photos by Troutnut from the Yakima River in Washington

The Yakima River in Washington
The Yakima River in Washington

Closeup insects by Troutnut from the Yakima River and the East Fork Issaquah Creek in Washington

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