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The Specimen

Rhithrogena morrisoni (Western March Brown) Mayfly SpinnerRhithrogena morrisoni (Western March Brown) Mayfly Spinner View 9 Pictures
Collected June 22, 2017 from the South Fork Snoqualmie River in Washington
Added to Troutnut.com by on June 23, 2017

The Discussion

Post Reply
TroutnutJune 23rd, 2017, 10:32 am
Administrator
Bellevue, WA

Posts: 2737		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
TaxonJuly 4th, 2017, 7:47 pm
Site Editor
Royse City, TX

Posts: 1350		Hi Jason-

Based on the shape of its penes, I believe Rhitrogena morrisoni is most likely.  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.  Please see page 194 of Western Mayfly Hatches by Rick Hafele and Dave Hughes.
Best regards,
Roger Rohrbeck
www.FlyfishingEntomology.com
TroutnutJuly 4th, 2017, 11:07 pm
Administrator
Bellevue, WA

Posts: 2737		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
CrepuscularJuly 5th, 2017, 5:00 am
Boiling Springs, PA

Posts: 923		Nice. I like seeing these west coast mayflies. Hopefully one day I'll se them in person! Thanks for posting.


Be well,
Eric

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