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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.

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.
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Female Siphlonurus occidentalis (Gray Drake) Mayfly Spinner Pictures

Lateral view of a Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from the Henry's Fork of the Snake River in Idaho
Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from the Henry's Fork of the Snake River in Idaho
Ventral view of a Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from the Henry's Fork of the Snake River in Idaho
Ruler view of a Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from the Henry's Fork of the Snake River in Idaho The smallest ruler marks are 1 mm.
Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from the Henry's Fork of the Snake River in Idaho
Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from the Henry's Fork of the Snake River in Idaho
Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from the Henry's Fork of the Snake River in Idaho
Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from the Henry's Fork of the Snake River in Idaho
Female Siphlonurus occidentalis (Siphlonuridae) (Gray Drake) Mayfly Spinner from the Henry's Fork of the Snake River in Idaho

This mayfly was collected from the Henry's Fork of the Snake River in Idaho on July 31st, 2020 and added to Troutnut.com by Troutnut on August 16th, 2020.


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Female Siphlonurus occidentalis (Gray Drake) Mayfly Spinner Pictures

Collection details
Location: Henry's Fork of the Snake River, Idaho
Date: July 31st, 2020
Added to site: August 16th, 2020
Author: Troutnut
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