Header image
Enter a name
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.

Case view of a Pycnopsyche guttifera (Limnephilidae) (Great Autumn Brown Sedge) Caddisfly Larva from the Yakima River in Washington
It's only barely visible in one of my pictures, but I confirmed under the microscope that this one has a prosternal horn and the antennae are mid-way between the eyes and front of the head capsule.

I'm calling this one Pycnopsyche, but it's a bit perplexing. It seems to key definitively to at least Couplet 8 of the Key to Genera of Limnephilidae Larvae. That narrows it down to three genera, and the case seems wrong for the other two. The case looks right for Pycnopsyche, and it fits one of the key characteristics: "Abdominal sternum II without chloride epithelium and abdominal segment IX with only single seta on each side of dorsal sclerite." However, the characteristic "metanotal sa1 sclerites not fused, although often contiguous" does not seem to fit well. Those sclerites sure look fused to me, although I can make out a thin groove in the touching halves in the anterior half under the microscope. Perhaps this is a regional variation.

The only species of Pycnopsyche documented in Washington state is Pycnopsyche guttifera, and the colors and markings around the head of this specimen seem to match very well a specimen of that species from Massachusetts on Bugguide. So I am placing it in that species for now.

Whatever species this is, I photographed another specimen of seemingly the same species from the same spot a couple months later.
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.

Female Stenonema modestum (Cream Cahill) Mayfly Spinner Pictures

Although I couldn't key out this female spinner, I'm fairly comfortable calling her Stenonema modestum based on the markings on the abdomen and their similarity to those on the males of this species. This one probably came from the Namekagon River, although there's a possibility it came from the West Fork of the Chippewa River, because it was found in the truck after fishing those streams on back-to-back days.

Lateral view of a Female Stenonema modestum (Heptageniidae) (Cream Cahill) Mayfly Spinner from the Namekagon River in Wisconsin
Female Stenonema modestum (Heptageniidae) (Cream Cahill) Mayfly Spinner from the Namekagon River in Wisconsin
Dorsal view of a Female Stenonema modestum (Heptageniidae) (Cream Cahill) Mayfly Spinner from the Namekagon River in Wisconsin
Female Stenonema modestum (Heptageniidae) (Cream Cahill) Mayfly Spinner from the Namekagon River in Wisconsin
Ruler view of a Female Stenonema modestum (Heptageniidae) (Cream Cahill) Mayfly Spinner from the Namekagon River in Wisconsin The smallest ruler marks are 1 mm.
Ventral view of a Female Stenonema modestum (Heptageniidae) (Cream Cahill) Mayfly Spinner from the Namekagon River in Wisconsin

This mayfly was collected from the Namekagon River in Wisconsin on June 22nd, 2021 and added to Troutnut.com by Troutnut on June 24th, 2021.


Start a Discussion of Spinner

Female Stenonema modestum (Cream Cahill) Mayfly Spinner Pictures

Collection details
Location: Namekagon River, Wisconsin
Date: June 22nd, 2021
Added to site: June 24th, 2021
Author: Troutnut
Troutnut.com is copyright © 2004-2024 (email Jason). privacy policy