Sunday, November 13, 2016

Flatheads and Perlids -- that's about it at the moment

Yesterday, I hit the Rivanna at Crofton: today, it was a small stream in Sugar Hollow.  And, at both streams I found much the same thing: common stoneflies, Acroneuria abnormis in both cases, and flatheaded mayflies -- but not the same species.  In the photo above, the "brown" form on A. abnormis.  So, so broad, a very unusual shape.  But it made for some very good photos.

And the flatheads I found in the Rivanna were -- like those in Buck Mt. Creek -- Maccaffertium modestum.


Different habitat, different results.  In Sugar Hollow today, it was the "patterned" form of A. abnormis.

And the flatheads out there were Maccaffertium pudicum, a species with a much different tolerance value (2.1 vs. the 5.7 of M. modestum).

To be fair, I did find other insects.  I saw giant stones at both of the streams, P. dorsata at the Rivanna and P. proteus in Sugar Hollow.  And at the Rivanna, I found another Acroneuria arenosa/evoluta, the one with anal gills present.

And there were Goera larvae (weighted case-makers) in our small mountain stream.

But the story at the moment seems to be Acroneuria stones and Maccaffertium flatheads.  Things will be changing real soon.

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