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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.

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.
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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Epeorus vitreus (Sulphur) Mayfly Nymph Pictures

Key features I discerned with a microscope include that the femoral flange is sharp, and the first gill is not extended.

This mayfly was collected from unknown in Wisconsin on February 7th, 2004 and added to Troutnut.com by Troutnut on January 25th, 2006.


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Epeorus vitreus (Sulphur) Mayfly Nymph Pictures

Collection details
Location: unknown, Wisconsin
Date: February 7th, 2004
Added to site: January 25th, 2006
Author: Troutnut
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