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.

Sunlight perfectly strikes the trees at a bend in the Foss River in the Washington Cascades.

From the Foss River in Washington

Stream photos

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Holocentropus Caddisfly Larva Holocentropus Caddisfly Larva

Dorsal view of a Holocentropus (Polycentropodidae) Caddisfly Larva from the Yakima River in Washington

This one seems to tentatively key to Holocentropus, although I can't make out the anal spines in Couplet 7 of the Key to Genera of Polycentropodidae Larvae nor the dark bands in Couplet 4 of the Key to Genera of Polycentropodidae Larvae, making me wonder if I went wrong somewhere in keying it out. I don't see where that could have happened, though. It might also be that it's a very immature larva and doesn't possess all the identifying characteristics in the key yet. If Holocentropus is correct, then Holocentropus flavus and Holocentropus interruptus are the two likely possibilities based on range, but I was not able to find a description of their larvae.

11 Recently Added Photos

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.

mean one thing, write another?

Male Onocosmoecus unicolor (Great Late-Summer Sedge) Caddisfly Adult

15 Pictures

Lateral view of a Male Onocosmoecus unicolor (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Adult from the Yakima River in Washington

I first just assumed this was Dicosmoecus based on anglers' conventional wisdom since it's a large orange "October caddis," but Creno set me straight. I should have keyed it out. After another look under the microscope, it lacks an anepisternal wart on the mesopleuron, which rules out Dicosmoecus. The midtibiae have 2 apical spurs and 1 pre-apical spur, and from there the color pattern of the wing points to Onocosmoecus. The location then narrows the species to unicolor.

Collected September 16, 2020 from the Yakima River in Washington

Added by Troutnut on September 18, 2020

Collected September 16, 2020 from the Yakima River in Washington and added by Troutnut on September 18, 2020

Creno
Grants Pass, OR

Posts: 302

Creno on Sep 19, 2020September 19th, 2020, 9:19 am EDT

Onocosmoecus unicolor?

Troutnut

Administrator
Bellevue, WA

Posts: 2758

Troutnut on Sep 19, 2020September 19th, 2020, 10:19 am EDT

Didn't mean one thing and write another -- you caught me assuming the genus based on angler-entomology instead of keying it out. Oops! After closer inspection under the microscope, of course you're right.

Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

Creno
Grants Pass, OR

Posts: 302

Creno on Sep 20, 2020September 20th, 2020, 7:19 am EDT

Interesting that the western angling lit has Dicosmoecus as orange. Within the Dicosmoecinae only Onocosmoecus is orange, the rest are dark greys to blacks when alive and, like Onocosmoecus, often faded to browns when pinned. Amphicosmoecus could be considered orangish on some speciemens but the wings are typically more grey/brown with a reddish tint, and finely speckled. Onocosmoecus unicolor is one of those very widespread species that further study will likely reveal are comprised of several species. But not to worry, it probably won't happen soon :-) I forgot to mention - thanks for the great pics.