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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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Baetisca obesa (Armored Mayfly) Mayfly Nymph Pictures

Baetisca obesa (Baetiscidae) (Armored Mayfly) Mayfly Nymph from the Neversink River (above reservoir) in New York
Baetisca obesa (Baetiscidae) (Armored Mayfly) Mayfly Nymph from the Neversink River (above reservoir) in New York
Baetisca obesa (Baetiscidae) (Armored Mayfly) Mayfly Nymph from the Neversink River (above reservoir) in New York
Baetisca obesa (Baetiscidae) (Armored Mayfly) Mayfly Nymph from the Neversink River (above reservoir) in New York
Baetisca obesa (Baetiscidae) (Armored Mayfly) Mayfly Nymph from the Neversink River (above reservoir) in New York
Lateral view of a Baetisca obesa (Baetiscidae) (Armored Mayfly) Mayfly Nymph from the Neversink River (above reservoir) in New York
Artistic view of a Baetisca obesa (Baetiscidae) (Armored Mayfly) Mayfly Nymph from the Neversink River (above reservoir) in New York
Dorsal view of a Baetisca obesa (Baetiscidae) (Armored Mayfly) Mayfly Nymph from the Neversink River (above reservoir) in New York
Baetisca obesa (Baetiscidae) (Armored Mayfly) Mayfly Nymph from the Neversink River (above reservoir) in New York
Ventral view of a Baetisca obesa (Baetiscidae) (Armored Mayfly) Mayfly Nymph from the Neversink River (above reservoir) in New York
Baetisca obesa (Baetiscidae) (Armored Mayfly) Mayfly Nymph from the Neversink River (above reservoir) in New York
Baetisca obesa (Baetiscidae) (Armored Mayfly) Mayfly Nymph from the Neversink River (above reservoir) in New York
Ruler view of a Baetisca obesa (Baetiscidae) (Armored Mayfly) Mayfly Nymph from the Neversink River (above reservoir) in New York The smallest ruler marks are 1 mm.

This mayfly was collected from the Neversink River (above reservoir) in New York on May 6th, 2007 and added to Troutnut.com by Troutnut on May 10th, 2007.


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Baetisca obesa (Armored Mayfly) Mayfly Nymph Pictures

Collection details
Location: Neversink River (above reservoir), New York
Date: May 6th, 2007
Added to site: May 10th, 2007
Author: Troutnut
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