Wednesday, January 18, 2012

A Day at the Rapidan River: Taking Pictures in the Snow

Well, at least it was sunny when I set off for the stream.  Butt when I reached the Rapidan River it was cold and windy, and as I worked, the clouds built up and it actually started to snow!

Not a lot to report today, except that all the spring insects are getting bigger and bigger.  And, in terms of biodiversity this is hands down, the best stream I know in our region.  I tried to get some good photos of course, but I didn't photograph the giant stoneflies, the common stoneflies, the roach-like stoneflies, the pronggilled mayflies, the brushlegged mayflies, craneflies, midges, blackflies, etc.  I did click a freeliving caddisfly larva -- Rhyacophila fuscula -- since it was so big (over an inch), but I almost skipped over that one as well.

I'll post my best photos, but I have to note right away that I had a major disappointment.  I found a fairly large Perlodid stonefly, Isogenoides hansoni.  I found small ones here on 9/13 and 10/22 -- but this one was fully colored and patterned.  But whether through bad handling or in some other way, the nymph had lost a leg and a tail.  Very discouraging to miss a chance like that at a very good photo, and, I like to harm these insects as little as possible.  Alas!  Let's hope there will be another chance on my next trip up to this stream.

For what it's worth -- Isogenoides hansoni.   This is not a Perlodid species that is easy to find.

And now for the rest.

1. In the photo at the top of the page, the Spiny Crawler mayfly, Ephemerella subvaria.  (For smaller nymphs found this season, see the postings of 9/13 and 10/22.)  And here's a shot of this nymph side-by-side with an Ephemerella subvaria.

The E. subvarias will form the "Hendrickson" hatch in March and April; E. dorotheas hatch as the "Pale Evening Duns" of April and May.

2. A beautiful, fully mature, small minnow mayfly -- Baetis pluto.  Not the small minnow species I'm expecting to see at this time of the year.

3. Fully mature large winter stoneflies -- Taeniopteryx burksi -- one with black wing pads and one with tan wing pads  (why are they tan?), and the one wanted to show off its coxal gills.

4. A quite handsome, quite large, freeliving caddisfly larva (R. fuscula).

5. A Uenoid case-maker -- which had managed to find some red pebbles to adorn the top of its case!

6. A lovely, big, Perlodid stonefly, Helopicus subvarians.

7. One of over a dozen Isoperla namata Perlodid stoneflies I found today.  They're really coming on strong.  Note how the dark brown abdominal stripes now stand out very clearly.

8. And finally, one of the things I was hoping to see, a tiny Nemourid stonefly, genus Prostoia (?).

There were also a lot of Epeorus pleuralis flatheaded mayflies crawling around on the bottoms of rocks.  I'll take their photos when they get bigger.

This is a stream that I always leave before I'm ready.

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