Sunday, June 15, 2014
The flatheads of summer: Entry Run and South River
We've reached the time of year when I like to get out of the small mountain streams: my focus turns to the summer small minnow mayflies which tend to inhabit larger streams, being more tolerant of warmer waters. But, we're still waiting for those streams and rivers to clear.
So, my Father's Day present was a trip up to Greene county to explore Entry Run and South River. What I found was no big surprise -- lots of flatheaded mayflies on the bottoms of rocks: Leucrocutas, Epeorus Vitreus, and Epeorus fragilis.
In the photo at the top of the page, the common Epeorus we find in the summer, E. vitreus. We often find it in the very same streams in which, in the winter and spring, we find Epeorus pleuralis. To ID these nymphs, all you have to do is look at the front edge of the head: "Head with distinctive color pattern of four irregular pale spots on anterior margin." (Beaty, "The Ephemeroptera of North Carolina," p. 17.) Easy to see.
And the other flathead that's common at this time of year in our clean mountain streams -- usually in the smallest of streams -- is Leucrocuta. I saw a lot of them today. Leucrocutas are tiny (6-8 mm) and hard to pick up and keep them intact. But I managed to get some good photos today.
If you follow this blog in a regular way, you know that Beaty urges us to keep Leucrocuta ID at the level of genus. Still, there are two sources that would call label the nymphs that I found today Leucrocuta hebe. (See Knopp and Cormier, Mayflies, p. 152, and the photos posted by Chandler:
http://www.discoverlife.org/mp/20q?search=Leucrocuta+hebe.) The key feature -- the pale "U-shaped" spots on several abdominal terga.
I also saw at least one Epeorus fragilis -- but I didn't get a very good photo.
Just a few other things.
1. There and fewer and fewer E. dorothea spiny crawlers around as most have hatched as Pale Evening Duns. But I did snap some shots of a male and a female.
2. Another left over from spring: Perlodid stonefly, Isoperla holochlora.
3. And one of the common netspinners that are quite "common" during the summer, Ceratopsyche slossonae.
While the head appears to be totally dark brown/black, there's actually a pale yellow spot right in the middle.