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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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Male Ephemerella aurivillii Mayfly Spinner Pictures

This spinner molted from a dun after being photographed, and the dun form is listed here as a separate specimen. I've rarely found a more cooperative and photogenic mayfly.

Lateral view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska
Dorsal view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska
Artistic view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska
Ventral view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska
Ruler view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska The smallest ruler marks are 1 mm.
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska
Artistic view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska
Here's the skin the dun shed as it molted into this spinner.

Male Ephemerella aurivillii (Ephemerellidae) Mayfly Spinner from Nome Creek in Alaska

This mayfly was collected from Nome Creek in Alaska on July 10th, 2011 and added to Troutnut.com by Troutnut on July 16th, 2011.

Discussions of this Spinner

This is one of my favorite mayfly photo sets
10 replies
Posted by Troutnut on Jul 16, 2011
Last reply on Jul 17, 2011 by Oldredbarn
Gotta love Ephemerella spinners! I was thrilled that this one emerged and molted intact, and then behaved so well in front of the camera.

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Male Ephemerella aurivillii Mayfly Spinner Pictures

Collection details
Location: Nome Creek, Alaska
Date: July 10th, 2011
Added to site: July 16th, 2011
Author: Troutnut
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