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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Setvena wahkeena (Wahkeena Springfly) Stonefly Nymph Setvena wahkeena (Wahkeena Springfly) Stonefly Nymph

Dorsal view of a Setvena wahkeena (Perlodidae) (Wahkeena Springfly) Stonefly Nymph from Mystery Creek #199 in Washington

As far as I can tell, this species has only previously been reported from one site in Oregon along the Columbia gorge. However, the key characteristics are fairly unmistakable in all except for one minor detail:
— 4 small yellow spots on frons visible in photos
— Narrow occipital spinule row curves forward (but doesn’t quite meet on stem of ecdysial suture, as it's supposed to in this species)
— Short spinules on anterior margin of front legs
— Short rposterior row of blunt spinules on abdominal tergae, rather than elongated spinules dorsally
I caught several of these mature nymphs in the fishless, tiny headwaters of a creek high in the Wenatchee Mountains.

7 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.

Troutnut is a project started in 2003 by salmonid ecologist Jason "Troutnut" Neuswanger to help anglers and fly tyers unabashedly embrace the entomological side of the sport. Learn more about Troutnut or support the project for an enhanced experience here.

This is not Ephemera simulans

Hexagenia limbata (Hex) Mayfly Nymph

4 Pictures

Dorsal view of a Hexagenia limbata (Ephemeridae) (Hex) Mayfly Nymph from the Marengo River in Wisconsin

Collected June 4, 2005 from the Marengo River in Wisconsin

Added by Troutnut on May 25, 2006

Collected June 4, 2005 from the Marengo River in Wisconsin and added by Troutnut on May 25, 2006

Beardius
Posts: 19

Beardius on Aug 1, 2008August 1st, 2008, 6:45 am EDT

This looks to be either Hexagenia or Litobrancha based upon the frontal process being rounded and not forked. Probably is Hexagenia based upon where it was collected and Hexagenia being so widespread and common, but I cannot tell from the photo if the gill on the first abdominal segment is forked or single from these photos.

Troutnut

Administrator
Bellevue, WA

Posts: 2758

Troutnut on Aug 1, 2008August 1st, 2008, 10:26 pm EDT

You're right. I can't see how I would possibly have misidentified this one, so I must have just absent-mindedly clicked it into the wrong category when I added it to the site.

Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist