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Lateral view of a Female Hexagenia limbata (Ephemeridae) (Hex) Mayfly Dun from the Namekagon River in Wisconsin
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.

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.

Isoperla fusca (Yellow Sally) Stonefly Nymph Pictures

This specimen represents a common find in a late-April sample from the far upper Yakima River. It seems to be the same species as another one I collected previously. Of the species keyed in Szczytko & Stewart 1979, it probably matches Isoperla fusca closest, but there's a good chance it's a species that wasn't in the key. The leg segments have a fringe of fine hairs which is supposed to be absent in Isoperla fusca, and the four dark stripes of the mesonotum and metanotum don't continue as 4 separate stripes on the pronotum as they should in the description of fusca. It's possible fusca is more variable than previously described, or this is a different species not included in that key. It's also worth noting there's definitely no fringe of fine setae on any part of the cerci, just the whorls of little stout ones around segment bases.

Ruler view of a Isoperla fusca (Perlodidae) (Yellow Sally) Stonefly Nymph from the Yakima River in Washington The smallest ruler marks are 1 mm.
Dorsal view of a Isoperla fusca (Perlodidae) (Yellow Sally) Stonefly Nymph from the Yakima River in Washington
Isoperla fusca (Perlodidae) (Yellow Sally) Stonefly Nymph from the Yakima River in Washington
Isoperla fusca (Perlodidae) (Yellow Sally) Stonefly Nymph from the Yakima River in Washington
Isoperla fusca (Perlodidae) (Yellow Sally) Stonefly Nymph from the Yakima River in Washington
Isoperla fusca (Perlodidae) (Yellow Sally) Stonefly Nymph from the Yakima River in Washington
Isoperla fusca (Perlodidae) (Yellow Sally) Stonefly Nymph from the Yakima River in Washington
Isoperla fusca (Perlodidae) (Yellow Sally) Stonefly Nymph from the Yakima River in Washington
Isoperla fusca (Perlodidae) (Yellow Sally) Stonefly Nymph from the Yakima River in Washington
Isoperla fusca (Perlodidae) (Yellow Sally) Stonefly Nymph from the Yakima River in Washington
Isoperla fusca (Perlodidae) (Yellow Sally) Stonefly Nymph from the Yakima River in Washington
Isoperla fusca (Perlodidae) (Yellow Sally) Stonefly Nymph from the Yakima River in Washington

This stonefly 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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Isoperla fusca (Yellow Sally) Stonefly Nymph Pictures

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