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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 Glossosoma (Glossosomatidae) (Little Brown Short-horned Sedge) Caddisfly Larva from the Yakima River in Washington
I caught this tiny larva without a case, but it seems to key pretty clearly to to Glossosomatidae. From there, the lack of sclerites on the mesonotum points to either Glossosoma or Anagapetus. Although it's difficult to see in a 2D image from the microscope, it's pretty clear in the live 3D view that the pronotum is only excised about 1/3 of its length to accommodate the forecoxa, not 2/3, which points to Glossosoma at Couplet 5 of the Key to Genera of Glossosomatidae 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 Dun Pictures

This is the most widespread species of Ephemerella, and also the most abundant in some places, but nobody I've talked to seemed to know what its duns looked like, and there were no pictures of its duns online or in any angling books. That mystery is solved with this male dun, which hatched from a definitively identified nymph.

Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from Nome Creek in Alaska
Lateral view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from Nome Creek in Alaska
Ventral view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from Nome Creek in Alaska
Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from Nome Creek in Alaska
Dorsal view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from Nome Creek in Alaska
Artistic view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from Nome Creek in Alaska
Ruler view of a Male Ephemerella aurivillii (Ephemerellidae) Mayfly Dun from Nome Creek in Alaska The smallest ruler marks are 1 mm.

This mayfly was collected from Nome Creek in Alaska on July 10th, 2011 and added to Troutnut.com by Troutnut on July 12th, 2011.


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Male Ephemerella aurivillii Mayfly Dun Pictures

Collection details
Location: Nome Creek, Alaska
Date: July 10th, 2011
Added to site: July 12th, 2011
Author: Troutnut
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