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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 Neoleptophlebia (Leptophlebiidae) Mayfly Nymph from the Yakima River in Washington
Some characteristics from the microscope images for the tentative species id: The postero-lateral projections are found only on segment 9, not segment 8. Based on the key in Jacobus et al. (2014), it appears to key to Neoleptophlebia adoptiva or Neoleptophlebia heteronea, same as this specimen with pretty different abdominal markings. However, distinguishing between those calls for comparing the lengths of the second and third segment of the labial palp, and this one (like the other one) only seems to have two segments. So I'm stuck on them both. It's likely that the fact that they're immature nymphs stymies identification in some important way.
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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Female Eurylophella (Chocolate Dun) Mayfly Spinner Pictures

I'm not sure of the species of this female spinner, and unfortunately I never found the associated males or duns to aid in identification. The egg-laying flight and fall of fairly large clouds of these females caused good rises of choosy trout for a week or so around early July on a large, cold spring creek in the northwoods. There is a distinctive stripe down the female's back, identical to that on this specimen collected a month later.

Lateral view of a Female Eurylophella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Bois Brule River in Wisconsin
Artistic view of a Female Eurylophella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Bois Brule River in Wisconsin
Dorsal view of a Female Eurylophella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Bois Brule River in Wisconsin
Ruler view of a Female Eurylophella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Bois Brule River in Wisconsin The smallest ruler marks are 1/16".
Female Eurylophella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Bois Brule River in Wisconsin
Ventral view of a Female Eurylophella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Bois Brule River in Wisconsin

This mayfly was collected from the Bois Brule River in Wisconsin on July 1st, 2005 and added to Troutnut.com by Troutnut on April 22nd, 2006.


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Female Eurylophella (Chocolate Dun) Mayfly Spinner Pictures

Collection details
Location: Bois Brule River, Wisconsin
Date: July 1st, 2005
Added to site: April 22nd, 2006
Author: Troutnut
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