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Hex Mayflies
Hexagenia limbata

The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large Brown Trout that only touch streamers for the rest of the year.

Exploring up the Skykomish

By Troutnut on September 10th, 2020
I've been meaning to check out the scenic country headwaters of the Skykomish for a while, more for the scenery and variety than for the fish, which I expected to be mostly the same 6-12" rainbows and coastal cutthroats found in all the other rivers on the west slope of the Washington cascades. I was also looking to practice Euro nymphing some more, and the Foss River has some ideal stretches of pocket water for that. Starting late in the morning, I was successful early and often. Then, toward mid afternoon, the action shut down completely. I went from catching fish in every pocket to seeing no sign of them in extremely inviting pools. The water temperature was optimal, but the fish were just off.

For the last hour of daylight I drove to the South Fork Skykomish and fished a couple of promising pools. Fish finally started rising intensely right at dusk (to what, I'm not sure), and I caught six small rainbows on dries.

Throughout the day there were no noteworthy hatches, but I did find a couple of bugs worth photographing. I'm especially curious what a near-mature Ephemerellid nymph was doing in the river in mid-September, but I've not yet had time to put most of my recently collected specimens under the microscope and see what they are.

Photos by Troutnut from the Foss River and the South Fork Skykomish River in Washington

Closeup insects by Troutnut from the Foss River in Washington

Male Doroneuria baumanni (Golden Stone) Stonefly Adult
I found this stonefly on some streamside vegetation. I didn't see any in the air in several hours of fishing.
Ephemerella aurivillii  Mayfly Nymph
This is a puzzling one to identify and I'm not sure about the species. The maxillary palp is present and segmented, and the maxillary canines are not strongly serrate laterally. I think it's Ephemerella, not Serratella. The ventral lamellae of the gills on abdominal segment 6 have a clear median notch with a depth at least half the length of the lamellae, which points toward a couple of uncommon species (most likely Ephemerella alleni), but the abdominal tubercles and coloration don't fit that species. To add to the confusion, none of the above species are expected to emerge in the fall, as far as I know. I'm going to call this one Ephemerella aurivillii for now, but that's highly uncertain.
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