Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
mayfly - unident - Ephemerella invaria

mayfly - unident - Ephemerella invaria
Selkirk/Brauer Field Station, Albany County, New York, USA
June 24, 2015
Size: 10 mm +/-
Came to lights.
No better photos. Dump if need be.

Moved from Mayflies.

This photo poses a particularly difficult challenge, at least for me.

It appears to have only 2 tails, but of course, a third tail could either be missing or simply not be in view. It appears to have streak of pigmentation (vittae) on the posterior half of the leading edge of the fore wings. It appears to have normal sized hind wings.

Putting those clues together leads me to suspect this female imago is either Heptageniid genus Epeorus, or Ephemerellid genus Eurylophella, or some obscure genus with which I am not familiar.

Thanks. Too bad I couldn't g
Thanks. Too bad I couldn't get a better photo. This thing was small and too active.

Body length

I assume the estimated size of 10 mm does not also include the length of the tails. Is that correct?

You are correct.
You are correct.


Have requested a 2nd opinion from a fellow aquatic insect enthusiast; will share his opinion once received.

Ephemerella invaria
Kurt Schirmer, my fellow aquatic insect enthusiast friend commented as follows: Looks like Ephemerella dorothea to me, though missing a tail. Interesting variation of pigmentation in the stigmatic region.

However, after further study on my part, I am leaning toward Ephemerella invaria, where I will place it in the guide.