Sunday, October 30, 2016

The Rapidan River: just the usual "unusual" and "rare" stoneflies and mayflies this morning

And they were abundant.  Above, the common stonefly, Agnetina capitata: there were a lot of them in the leafpacks this morning.  Still very small at this time of year.  Key features: complete row of setae on the occipital ridge (back of the head), anal gills present, terga banded - posterior margins dark, tergite 10 pale, with dark pigmentation mesally .  For the description, see Steve Beaty, "The Plecoptera of North Carolina," vers. 4.0, p. 40.

This species was listed as "significantly rare" in North Carolina in 2010.  Here are some additional photos.


And then there's the spiny crawler mayfly that we see up here every year which is also listed as "rare," Ephemerella subvaria.  Very, very small at the moment.

The small minnow mayfly that managed to get into this photo -- not really rare: Baetis pluto (male).  Should be a good hatch of Blue-winged Olives up here in the fall.


And another stonefly that gets marked as "uncommon" -- the Perlodid stonefly, Isogenoides hansoni.  Note that the posterior edges of the wingpads are still pretty much straight across.


I was surprised to see so many stoneflies this morning.  My finds included this big common stone, Acroneuria carolinensis.

It's not uncommon, but we only see it in quality mountain streams.  Tolerance value of 1.2.  (A. capitata, E. subvaria, and I. hansoni are all too uncommon to be assigned tolerance values.)

Great to get back to the streams -- and great to be getting some photos again.

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