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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.

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Male Epeorus deceptivus Mayfly Dun Pictures

The lack of a darkened humeral crossvein rules out Epeorus albertae and Epeorus dulciana. The lack of a dark macula on the forefemora rules out Epeorus longimanus. The small size rules out Epeorus grandis and Epeorus permagnus. That leaves as the only possibility known in Washington state Epeorus deceptivus. It is a small species, although not reportedly quite as small as this specimen. I couldn't find anything in the species description in Traver (1935) to definitively confirm or rule out the species ID, given that I don't have the preserved specimen to check under a microscope, but it has to be either deceptivus or something not yet reported in Washington.

It was collected at the same time as a similar-sized female dun.

This mayfly was collected from the South Fork Sauk River in Washington on July 5th, 2017 and added to Troutnut.com by Troutnut on July 6th, 2017.

Discussions of this Dun

ID on this one?
Posted by Troutnut on Jul 6, 2017
Last reply on Jul 6, 2017 by Troutnut
See the caption for the specimen -- I'm thinking Epeorus dulciana based on size and geographic distribution alone, but I can't find any information about how their duns look. Pretty mayfly, though!

Start a Discussion of Dun

Male Epeorus deceptivus Mayfly Dun Pictures

Collection details
Location: South Fork Sauk River, Washington
Date: July 5th, 2017
Added to site: July 6th, 2017
Author: Troutnut
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