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.

Stream photos

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Female Sweltsa borealis (Boreal Sallfly) Stonefly Adult Female Sweltsa borealis (Boreal Sallfly) Stonefly Adult

Lateral view of a Female Sweltsa borealis (Chloroperlidae) (Boreal Sallfly) Stonefly Adult from Harris Creek in Washington

I was not fishing, but happened to be at an unrelated social event on a hill above this tiny creek (which I never even saw) when this stonefly flew by me. I assume it came from there. Some key characteristics are tricky to follow, but process of elimination ultimately led me to Sweltsa borealis. It is reassuringly similar to this specimen posted by Bob Newell years ago. It is also so strikingly similar to this nymph from the same river system that I'm comfortable identifying that nymph from this adult. I was especially pleased with the closeup photo of four mites parasitizing this one.

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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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Female Drunella grandis (Western Green Drake) Mayfly Dun Pictures

I didn't find a male spinner to associate with this one; I'm tentatively calling it grandis based on size alone. I found it floating down the surface of the Henry's Fork (the only one I saw that day, weeks after the hatch probably peaked) crippled by what appears to be a mass of eggs sticking out of its abdomen.

Lateral view of a Female Drunella grandis (Ephemerellidae) (Western Green Drake) Mayfly Dun from the Henry's Fork of the Snake River in Idaho

Female Drunella grandis (Ephemerellidae) (Western Green Drake) Mayfly Dun from the Henry's Fork of the Snake River in Idaho

Ventral view of a Female Drunella grandis (Ephemerellidae) (Western Green Drake) Mayfly Dun from the Henry's Fork of the Snake River in Idaho

Dorsal view of a Female Drunella grandis (Ephemerellidae) (Western Green Drake) Mayfly Dun from the Henry's Fork of the Snake River in Idaho

Ruler view of a Female Drunella grandis (Ephemerellidae) (Western Green Drake) Mayfly Dun from the Henry's Fork of the Snake River in Idaho The smallest ruler marks are 1 mm.

This mayfly was collected from the Henry's Fork of the Snake River in Idaho on August 1st, 2020 and added to Troutnut.com by Troutnut on August 18th, 2020.

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