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.

Here Oksrukuyik Creek flows away from the Dalton Highway toward the pipeline. It eventually grows into one of the major rivers of the North Slope, and the main drainage to the west of the Sag, but where it crosses the road it's just a small grayling stream.

From Oksrukuyik Creek in Alaska

Stream photos

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Tricorythodes (Trico) Mayfly Nymph Tricorythodes (Trico) Mayfly Nymph

Dorsal view of a Tricorythodes (Leptohyphidae) (Trico) Mayfly Nymph from Mystery Creek #308 in Washington

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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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Tiny mayfly for ID

Isidro
Posts: 24

Isidro on Mar 27, 2008March 27th, 2008, 1:09 am EDT

I think that this one can be impossible...

Sabiñanigo, NE Spain. Fresh mountain-climate, about 900 meters. River: with many trees and hedges in the sides. Contaminated, slow, with some lime and big stones, without water weeds, not deep. Mayfly: about 11-12 mm. wingspan, Three cerci, of very clear colour, very dark body, turbinate eyes.

Some helps can be given?
Thanks
Isidro

Taxon

Site Editor
Plano, TX

Posts: 1311

Taxon on Mar 27, 2008March 27th, 2008, 3:09 am EDT

Isidro-

My guess would be a species in family Leptophlebiidae. The fact that the median filament is longer than the cerci should identify it rather easily for someone familiar with European mayflies. I recommend you ask Dr. Nikita J. Kluge of St. Petersburg University.

Edit: Now that I look at the photo again, I suspect the tails may actually be of equal length, and the angle of the photo makes it appear they are not. In any event, that impacts neither my guess as to family, nor my recommendation for consultation.

Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com

Isidro
Posts: 24

Isidro on May 4, 2008May 4th, 2008, 2:56 am EDT

Thanks Roger. I see that adult mayflies are more difficult taht I supposed...