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.

Of all the pools I've fished, this one was most deserving of the colorful little brook trout it held.

From Mystery Creek # 89 in New York

Stream photos

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Female Sweltsa borealis (Boreal Sallfly) Stonefly Adult Female Sweltsa borealis (Boreal Sallfly) Stonefly Adult

Lateral view of a Female Sweltsa borealis (Chloroperlidae) (Boreal Sallfly) Stonefly Adult from Harris Creek in Washington

I was not fishing, but happened to be at an unrelated social event on a hill above this tiny creek (which I never even saw) when this stonefly flew by me. I assume it came from there. Some key characteristics are tricky to follow, but process of elimination ultimately led me to Sweltsa borealis. It is reassuringly similar to this specimen posted by Bob Newell years ago. It is also so strikingly similar to this nymph from the same river system that I'm comfortable identifying that nymph from this adult. I was especially pleased with the closeup photo of four mites parasitizing this one.

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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.

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.

Second opinions on this one's ID?

Male Rhithrogena morrisoni (Western March Brown) Mayfly Spinner

9 Pictures

Lateral view of a Male Rhithrogena morrisoni (Heptageniidae) (Western March Brown) Mayfly Spinner from the South Fork Snoqualmie River in Washington

Collected June 21, 2017 from the South Fork Snoqualmie River in Washington

Added by Troutnut on June 23, 2017

Collected June 21, 2017 from the South Fork Snoqualmie River in Washington and added by Troutnut on June 23, 2017

Troutnut

Administrator
Bellevue, WA

Posts: 2758

Troutnut on Jun 23, 2017June 23rd, 2017, 6:32 am EDT

I tentatively keyed it out to Rhithrogena morrisoni based on Needham's Biology of Mayflies, but I'm not completely sure. Roger's website lists Rhithrogena emerging in Washington in March and April, and this one was collected June 22nd. But this did come from high up in a mountain stream after a year of very heavy snowpack, so it might be that far behind schedule. It also looks very much like the specimen Bob Newell posted from eastern Washington. What do Roger and others think?

Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

Taxon

Site Editor
Plano, TX

Posts: 1311

Taxon on Jul 4, 2017July 4th, 2017, 3:47 pm EDT

Hi Jason-

Based on the shape of its penes, I believe Rhitrogena morrisoni is most likely.Â As to its emergence in late June, my WA Aquatic Insect Emergence Chart is in error, as it should show emergence of various Rhitrogena species from early-Feb through mid-October.Â Please see page 194 of Western Mayfly Hatches by Rick Hafele and Dave Hughes.

Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com

Troutnut

Administrator
Bellevue, WA

Posts: 2758

Troutnut on Jul 4, 2017July 4th, 2017, 7:07 pm EDT

Thanks Roger. I checked with Bob Newell via email, to, and he concurred on the ID.

I suppose I should order a copy of Western Mayfly Hatches now that I live in the regular West.

Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist

Crepuscular