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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.

Lateral view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Yakima River in Washington
This specimen keys pretty easily to Onocosmoecus, and it closely resembles a specimen from Alaska which caddis expert Dave Ruiter recognized as this genus. As with that specimen, the only species in the genus documented in this area is Onocosmoecus unicolor, but Dave suggested for that specimen that there might be multiple not-yet-distinguished species under the unicolor umbrella and it would be best to stick with the genus-level ID. I'm doing the same for this one.
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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Rhithrogena virilis Mayfly Nymph Pictures

I'm tentatively calling this specimen Rhithrogena virilis, based on the incomplete key in The Biology of Mayflies which describes the correct body length (12 mm) and a purplish tinge on the dorsal half of the platelike gills. An early specimen posted by Bob Newell describes markings on the last couple abdominal tergites which also match this nymph.

Ruler view of a Rhithrogena virilis (Heptageniidae) Mayfly Nymph from the Yakima River in Washington The smallest ruler marks are 1 mm.
Ventral view of a Rhithrogena virilis (Heptageniidae) Mayfly Nymph from the Yakima River in Washington
Dorsal view of a Rhithrogena virilis (Heptageniidae) Mayfly Nymph from the Yakima River in Washington

This mayfly was collected from the Yakima River in Washington on April 24th, 2022 and added to Troutnut.com by Troutnut on April 27th, 2022.


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References

  • Needham, James G., Jay R. Traver, and Yin-Chi Hsu. 1935. The Biology of Mayflies. Comstock Publishing Company, Inc.

Rhithrogena virilis Mayfly Nymph Pictures

Collection details
Location: Yakima River, Washington
Date: April 24th, 2022
Added to site: April 27th, 2022
Author: Troutnut
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