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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.

Case view of a Pycnopsyche guttifera (Limnephilidae) (Great Autumn Brown Sedge) Caddisfly Larva from the Yakima River in Washington
It's only barely visible in one of my pictures, but I confirmed under the microscope that this one has a prosternal horn and the antennae are mid-way between the eyes and front of the head capsule.

I'm calling this one Pycnopsyche, but it's a bit perplexing. It seems to key definitively to at least Couplet 8 of the Key to Genera of Limnephilidae Larvae. That narrows it down to three genera, and the case seems wrong for the other two. The case looks right for Pycnopsyche, and it fits one of the key characteristics: "Abdominal sternum II without chloride epithelium and abdominal segment IX with only single seta on each side of dorsal sclerite." However, the characteristic "metanotal sa1 sclerites not fused, although often contiguous" does not seem to fit well. Those sclerites sure look fused to me, although I can make out a thin groove in the touching halves in the anterior half under the microscope. Perhaps this is a regional variation.

The only species of Pycnopsyche documented in Washington state is Pycnopsyche guttifera, and the colors and markings around the head of this specimen seem to match very well a specimen of that species from Massachusetts on Bugguide. So I am placing it in that species for now.

Whatever species this is, I photographed another specimen of seemingly the same species from the same spot a couple months later.
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.

Male Eurylophella minimella (Chocolate Dun) Mayfly Spinner Pictures

The genus ID on this specimen is confident but species is very tentative, based on the tentative ID of a seemingly-identical specimen from a nearby river a few days apart.

Lateral view of a Male Eurylophella minimella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Namekagon River in Wisconsin
Male Eurylophella minimella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Namekagon River in Wisconsin
Male Eurylophella minimella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Namekagon River in Wisconsin
Ventral view of a Male Eurylophella minimella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Namekagon River in Wisconsin
Male Eurylophella minimella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Namekagon River in Wisconsin
Male Eurylophella minimella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Namekagon River in Wisconsin
Dorsal view of a Male Eurylophella minimella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Namekagon River in Wisconsin
Male Eurylophella minimella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Namekagon River in Wisconsin
Male Eurylophella minimella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Namekagon River in Wisconsin
Male Eurylophella minimella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Namekagon River in Wisconsin
Male Eurylophella minimella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Namekagon River in Wisconsin
Male Eurylophella minimella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Namekagon River in Wisconsin
Male Eurylophella minimella (Ephemerellidae) (Chocolate Dun) Mayfly Spinner from the Namekagon River in Wisconsin

This mayfly was collected from the Namekagon River in Wisconsin on June 3rd, 2005 and added to Troutnut.com by Troutnut on May 24th, 2006.

Discussions of this Spinner

Not invaria
2 replies
Posted by GONZO on May 24, 2009
Last reply on May 24, 2009 by GONZO
This spinner is Eurylophella rather than E. invaria. The long 9th abdominal segment of Eurylophella is often the easiest way to avoid confusing the duns and spinners with Ephemerella. The claspers and genitalia of this male are also representative of Eurylophella.

Invaria Spinners
10 replies
Posted by Martinlf on Aug 9, 2007
Last reply on Aug 10, 2007 by JAD
These photos show a darker invaria spinner than I'm used to seeing. I know color varies a good bit in invaria nymphs and duns, so I suppose color variation is pretty wide with the spinners also, correct?

Start a Discussion of Spinner

Male Eurylophella minimella (Chocolate Dun) Mayfly Spinner Pictures

Collection details
Location: Namekagon River, Wisconsin
Date: June 3rd, 2005
Added to site: May 24th, 2006
Author: Troutnut
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