Wednesday, January 19, 2011

Stream Report: The Rapidan River (Madison County)

The Rapidan River is not in the watershed of the Rivanna River.  Still, it's a beautiful stream coming out of the National Park, and north of Wolftown, the drive goes through some gorgeous country.  And,
there are lots of insects in this one, many I don't see anywhere else.

The day's inventory:  1) lots and lots of flatheaded mayflies, genus Epeorus -- there will be a very good "Quill Gordon" hatch here in March and April!  2) I found some Stenonema flatheaded mayflies as well;
3) a few small winter stoneflies; 4) a lot of large winter stoneflies -- all genus Taeniopteryx; 5) lots of "Humpless" caddisflies (Brachycentridae); 6) a few Glossosomatids (Saddle case makers) and a few Uenoid case makers as well; 7) two common stoneflies -- genus Acroneuria; 8) a small minnow mayfly; 9) a brushlegged mayfly; 10) a prong-gilled mayfly; 11) and this spectacular (photo above) spiny crawler mayfly (family: Ephemerellidae)! 12) I also found some netspinners and one fingernet caddis -- genus Dolophilodes.  This is not a genus we normally find, and I'll post an entry on fingernets shortly.

Another treasure today was this HUGE Giant stonefly.  This was 1 3/4" - 2" long: and if you doubt the length, note the size of the large winter stonefly in the top of the picture!

My fly fishing books tell me this will be hatching sometime this spring -- but he already looks fully ready to crack open that case and fly away!

A few more photos.  The humpless caddisflies that I found were especially colorful -- both the larvae and the cases.  An example below.  This was a big one: the case was 3/4" long.

I put several Glossosomatids on my petri dish to get some photos and witnessed something I didn't expect to see.  This one couldn't resist putting his head out from under the front of his case to peak around.

Finally, one of my main reasons for making this trip was to look for Lepidostomatids.  Lepidostomatids are case making caddisflies that we normally only find in this kind of stream -- mountainous, small, and well forested.   And this is the time of year they're around.  I've been wanting to write a short piece on this lovely larva, but I wanted to get a live shot.  As you can see, I was successful.  More to come on this later.

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