This one was surprisingly straightforward to identify. The lack of a sclerite at the base of the lateral hump narrows the field quite a bit, and the other options followed fairly obvious characteristics to Clostoeca, which only has one species, Clostoeca disjuncta.
Leskorcala on Aug 24, 2020August 24th, 2020, 3:46 pm EDT
hello, In late July and first week of august I spotted many 2 winged mayflies spinners on the walls of my house (I live about 20 yards from the edge of Bitterroot river, MT ) All of the spinner adults had 2 tails
I have narrowed down by size, tail numbers,emergence to family Heptageniidea , Genus Empeours I believe its E. albertae species. The Slate cream dun
Hope someone can conform this for me. I am in process doing year long project identify all teh major hatches on my home river, hope to get it done next year.
Troutnut on Sep 3, 2020September 3rd, 2020, 6:35 pm EDT
Very nice pictures!
I think this probably is Epeorus. From the fourth picture, it looks like the first two tarsal segments are approximately the same length, which usually points to that genus.
I don't think the species is albertae, unless I have misidentified the specimens labeled as albertae on this site, including this one most recently. The coloration of the abdomen is very different, and I seem to recall the spots on the femora are a key feature of albertae as well.
Unfortunately I'm not sure what species it is, as I don't have my ID resources with me at the moment on a trip.
Jason Neuswanger, Ph.D.
Troutnut and salmonid ecologist
Leskorcala on Sep 10, 2020September 10th, 2020, 5:08 pm EDT
Thanks Jason for your feedback. this is very popular hatch on my home water , lot of anglers would call them PMD but the 2 tail is easy giveaway
sorry in my original post I said 2 winged mayfly ( I was referring to 2 tail mayfly ) anyway , I can see now looking at some references images where spots on femora are absent on this mayfly.