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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 Kogotus (Perlodidae) Stonefly Nymph from Mystery Creek #199 in Washington
This one pretty clearly keys to Kogotus, but it also looks fairly different from specimens I caught in the same creek about a month later in the year. With only one species of the genus known in Washington, I'm not sure about the answer to this ID.
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.

Male Ephemerella aurivillii Mayfly Dun Pictures

This dun was collected in proximity to this spinner, and to this female that looks like the same species.

Among western species, it most closely resembles Ephemerella aurivillii, of which I reared a specimen from a positively-identified nymph and photographed the male dun previously in Alaska. In the photos, this dun does not seem to have the same evidence of the nymph's dorsal stripe, but that's due to the lighting. A faint stripe is apparent under the microscope, as it is in the female linked above.

They do appear to be a bit short for aurivillii, with the male at 8 mm and the female at 9 mm, but the spinners could be a bit longer.

Among the other Ephemerella mayflies documented in Montana, Ephemerella alleni and Ephemerella mucronata are the only two others that seem to not be ruled out.

Lateral view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from the Madison River in Montana
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from the Madison River in Montana
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from the Madison River in Montana
Dorsal view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from the Madison River in Montana
Ruler view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from the Madison River in Montana The smallest ruler marks are 1 mm.
Artistic view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from the Madison River in Montana
Ventral view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from the Madison River in Montana

This mayfly was collected from the Madison River in Montana on July 1st, 2019 and added to Troutnut.com by Troutnut on July 18th, 2019.


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Male Ephemerella aurivillii Mayfly Dun Pictures

Collection details
Location: Madison River, Montana
Date: July 1st, 2019
Added to site: July 18th, 2019
Author: Troutnut
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