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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.

Lateral view of a Onocosmoecus (Limnephilidae) (Great Late-Summer Sedge) Caddisfly Larva from the Yakima River in Washington
This specimen keys pretty easily to Onocosmoecus, and it closely resembles a specimen from Alaska which caddis expert Dave Ruiter recognized as this genus. As with that specimen, the only species in the genus documented in this area is Onocosmoecus unicolor, but Dave suggested for that specimen that there might be multiple not-yet-distinguished species under the unicolor umbrella and it would be best to stick with the genus-level ID. I'm doing the same for this one.
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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Eurylophella (Chocolate Dun) Mayfly Nymph Pictures

It has the segment 4 gill and abdominal segment 9 is longer than segment 8. I couldn't see abdominal tubercles, but they may not yet be developed in such an early instar.

This mayfly was collected from unknown in Wisconsin on March 10th, 2004 and added to Troutnut.com by Troutnut on January 19th, 2006.


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Eurylophella (Chocolate Dun) Mayfly Nymph Pictures

Collection details
Location: unknown, Wisconsin
Date: March 10th, 2004
Added to site: January 19th, 2006
Author: Troutnut
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