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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.

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.
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.

Dorsal view of a Paragnetina media (Perlidae) (Embossed Stonefly) Stonefly Nymph from Cascadilla Creek in New York
GONZO
Site Editor
"Bear Swamp," PA

Posts: 1681
GONZO on Oct 4, 2006October 4th, 2006, 10:01 am EDT
The row of spinules, absence of anal gills, and overall hairiness are all consistent with immature P. media. (The mature nymphs are cleaner, darker, and less hairy.)

I would also suggest altering the Paragnetina page to say that media is very important in both the East and Midwest. (media is probably the most widespread and commonly encountered large member of the Perlidae in the East. Due to its tolerance and adaptability it is often found in streams that have few other stonefly species.) The "accepted" (Stark, et al.) common names are Embossed Stone for media and Beautiful Stone for immarginata.
Troutnut
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Administrator
Bellevue, WA

Posts: 2758
Troutnut on Oct 4, 2006October 4th, 2006, 10:19 am EDT
Thanks. I've made the suggested changes.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
Dkak
Posts: 1
Dkak on Jan 19, 2010January 19th, 2010, 4:37 am EST
I'm working with some of these "hairy" Paragnetina from Vermont right now. I've found them difficult to key out because their gills are only somewhat branched, ocelli are difficult to see on many individuals, and the inner fringe of long hairs on the cerci is not present (probably due to immaturity). These pictures helped a bunch!

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