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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 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.
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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Leadwings

This common name refers to only one genus. Click its scientific name to learn more.

Mayfly Genus Isonychia

These are sometimes called Leadwings.
Sporadic hatches are rarely as outstanding as those of Isonychia. On streams with good populations, they are reliably hatching in light numbers, here and there, for most of the evening through most of the mid- to late season.

The spinners, and occasionally the duns, produce more concentrated action, but the real value of the Isonychia hatch is its duration and the size of the flies; large trout become ever watchful for them, even when they aren't emerging.

All the species of Isonychia are similar in appearance and behavior.
Lateral view of a Female Isonychia bicolor (Isonychiidae) (Mahogany Dun) Mayfly Dun from the Namekagon River in Wisconsin
Lateral view of a Female Isonychia bicolor (Isonychiidae) (Mahogany Dun) Mayfly Spinner from the West Branch of Owego Creek in New York
I collected this female together with a male.
Dorsal view of a Isonychia bicolor (Isonychiidae) (Mahogany Dun) Mayfly Nymph from the Beaverkill River in New York

Leadwings

Scientific Name
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