Thursday, January 5, 2012

"Two" Large -- and Other Treats From South River

Yes, it's "two," not "too!"  I'm not sure how I managed to get them both into focus.  On the bottom, the large winter stonefly Taenionema atlanticum; at the top, the large winter stonefly, Taeniopteryx burksi.

I went to a new stream today, the South River, a small stream that flows out of the Blue Ridge and passes to the north of Stanardsville, VA.   I followed it up into the mountains, so it was not very big where I decided to stop and have a look at the insects.

Every rock I turned over was covered with flatheaded mayflies -- all Epeorus pleuralis -- and every leaf pack I looked at was crawling with large winter stoneflies, among other things.  Let's look at the show.

1. A Spiny Crawler mayfly -- Ephemerella dorothea.  I couldn't believe it!  I expect to see these in March -- our streams are loaded with them in March and April -- but January 5th?  You never know what you're going to see.

2. Another surprise -- another small minnow mayfly, but this one was Baetis pluto.  So, I've now seen this small minnow species in four different streams at four different times of the year -- in May, June, October, and January.  Note that the middle cercal segment (tail) is much shorter than those to the sides, and that tergum 5 is pale, while 6-8 are dark.

3. And another surprise -- a fully mature large winter stonefly, Taeniopteryx burksi.  Note the dark wing pads, which mean that this one is ready to break that skin open and fly.


4. And yet another surprise -- a green free living caddisfly larva, but it isn't Rhyacophila fuscula -- no dark, partial "H" on its head.   It's pretty wierd.  I've got to work on this one a bit, and if I figure it out, I'll let you know.  I took a quick look at Beaty ("The Trichoptera of North Carolina"), but I can find nothing described as having a head that's lime green.


The rest of my findings were things I'd expect to find in a quality, mountain, stream at this time of the year -- but things of beauty nonetheless.

1. The flatheaded mayfly -- Epeorus pleuralis.  This was probably the dominant taxon today: they were crawling all over the rocks.  They're easy to spot.  They do not move in a straight direction; they always angle off to the side, whether moving ahead or retreating.  And this is their season.  They will hatch in March and April as "Quill Gordons" (to fly fishermen).  Note the short wing pads -- and this is one of the larger nymphs that I saw.

2. Uenoid case-maker caddisflies.  I saw quite a few on the sides of the rocks, but just picked out this big one for taking a picture.  Pretty case.

3. Prong-gilled mayfly nymphs -- genus Paraleptophlebia.  There were a lot of them.

4. A Perlodid stonefly, genus Isoperla for sure, probably I. namata (but not a call I'm ready to make).

5. And, here are some more Taenionema atlanticum large winter stoneflies.  I did not see the large winter species Strophopteryx fasciata at all in this stream.

It was a long drive -- but well worth it.  I'll be heading back there next month.

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