Tuesday, October 18, 2011

Coming Soon to a Stream Near You: Large Winter Stoneflies (Taeniopterygidae)

... but I still haven't seen them.  Any day now, we should start to see "tiny" large winter stoneflies (Taeniopterygidae: genus Taeniopteryx), also "tiny" small winter stoneflies (Capniidae).  In fact, they're probably already there for me to find -- I'm just not seeing them yet.  When I do see them, they'll look something like this:

Just how small is that you say?  Well, here is a microscope view of the tiny large winter and a mature large winter side-by-side.

Mature large winter nymphs are about 1/2" long -- so "seeing" the "baby" large winters, and picking them up with your tweezers,  is no easy thing.  Still, even when they're tiny like this, with magnification -- even using a loupe at the stream -- the "coxal gills" that ID this genus of large winter stonefly are easy to see.

When we find them they'll be in the leaf packs -- which is one of the reasons they're hard to find at the moment.   We had 5 inches of rain at our house last Wednesday and Thursday, so the streams are still high and fast -- though they are running clear.  With that much rain, the leaf packs that had already built up were blown out and washed away and new ones are just now starting to form.

I went out to Buck Mt. Creek this morning in hopes of seeing some large winter stoneflies in leaves: I found nothing in the leaves -- in the few packs I could find -- but one lonely Darner dragonfly, of which I got a so-so photo.  (Note the tiny brushlegged mayfly clinging to its right side.)

I did find tiny insects on the bottoms of rocks and picked some up in hopes that they might be large winters.  But no -- they were tiny, tiny, flatheaded mayflies and tiny brushlegged mayflies.  I saw only one thing on the rocks with any size: a number of fingernet caddis larvae.

So, it's a waiting game.  Last year, I saw my first large winter stonefly (the one in the photo above) on October 29th: three years ago, we ran into them as early as the 12th of October.  So, we should meet with success very soon.

No comments:

Post a Comment