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.

Stream photos

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Neoleptophlebia Mayfly Nymph Neoleptophlebia Mayfly Nymph

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.

10 Recently Added Photos

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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Synonym of vitreus

This topic is about the Mayfly Genus Epeorus

There is remarkable variety of form and color within this prolific genus of fast-water mayflies. Different species are found across the country, and several cause good hatches. Fly anglers are likely to encounter the lesser species on occasion, too.

The best Epeorus hatch in the East is Epeorus pleuralis, the famous Quill Gordon, the first abundant large mayfly hatch of the year. Epeorus vitreus comes a little later and is important in both the East and Midwest.

In the West, Epeorus longimanus dominates in fast, high-altitude streams, while Epeorus albertae inhabits slower and lower waters.

Example specimens

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Male Epeorus albertae (Pink Lady) Mayfly Spinner

Lateral view of a Male Epeorus albertae (Heptageniidae) (Pink Lady) Mayfly Spinner from the North Fork Stillaguamish River in Washington

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Male Epeorus deceptivus Mayfly Dun

Artistic view of a Male Epeorus deceptivus (Heptageniidae) Mayfly Dun from the South Fork Sauk River in Washington

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.

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Female Epeorus albertae (Pink Lady) Mayfly Dun

Artistic view of a Female Epeorus albertae (Heptageniidae) (Pink Lady) Mayfly Dun from the North Fork Stillaguamish River in Washington

GONZO
Site Editor
"Bear Swamp," PA

Posts: 1681

GONZO on Oct 4, 2006October 4th, 2006, 7:27 am EDT

I believe rubidus = vitreus

Troutnut

Administrator
Bellevue, WA

Posts: 2758

Troutnut on Oct 4, 2006October 4th, 2006, 7:51 am EDT

Thanks. Good catch. That must be a recent change, or at least recently added to the mayfly species list at Purdue.

I have one small thing on my programming to-do list before I can make the change, but I'll do it soon.

Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

Taxon