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Artistic view of a Male Pteronarcys californica (Pteronarcyidae) (Giant Salmonfly) Stonefly Adult from the Gallatin River in Montana
Salmonflies
Pteronarcys californica

The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.

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.
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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Hexagenia limbata (Hex) Mayfly Nymph Pictures

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

This mayfly was collected from the Marengo River in Wisconsin on June 5th, 2005 and added to Troutnut.com by Troutnut on May 25th, 2006.

Discussions of this Nymph

This is not Ephemera simulans
1 replies
Posted by Beardius on Aug 1, 2008
Last reply on Aug 1, 2008 by Troutnut
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.

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Hexagenia limbata (Hex) Mayfly Nymph Pictures

Collection details
Location: Marengo River, Wisconsin
Date: June 5th, 2005
Added to site: May 25th, 2006
Author: Troutnut
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