Thursday, October 11, 2012

Crossing the Line Between "Macro" and "Micro": The Stonefly Season Begins

The Chinese have a saying -- 說曹操,曹操就來了 -- "Speak of Cao Cao and here he comes," sort of the equivalent of "Speak of the Devil..."!  (Cao Cao was a powerful general in ancient China, AD 155-220).

I told my good friend and bug hunting companion just this morning that we ought to see "tiny" small and large winter stoneflies (Capniidae and Taeniopterygidae) in our streams any day now.   I didn't see any large winters at Buck Mt. Creek, but the leaves were packed with extremely small, small winter stones.  The one in the photo above measured 3mm long and .3 mm wide.  At this stage of the game they look more like midges than stoneflies, and stream volunteers who see aquatic insects 2-3 times a year might not have seen them.  But, if you're out there sampling, they're here!  Fortunately they grow pretty quickly at this time of the year.  Here's the first nymph I found last year -- on 10/24:

And here's one from 11/2:

And, I found this one last year on 11/17 in Buck Mt. Creek.  So they grow up in a hurry!

I also found, this morning, a bunch of very small Perlodid stoneflies -- Helopicus subvarians -- the smallest I've ever seen.

Length -- about 2.5 mm.  I could have used my more powerful macro lens, but these photos aren't bad for insects that small.   Helopicus stoneflies grow at a much slower pace than the small and large winters: I'll see mature nymphs from February -- April.  This one (below) was collected on April 14th last year.  At maturity, they can be as long as 20 mm!


I did see some insects that were already mature -- several Baetis intercalaris small minnow mayflies including this beauty.

But it's the new generation of stoneflies that got me excited (I also had a tiny Clioperla clio Perlodid that fell out of my bowl when I stumbled!).    Finally, something in the streams in large numbers, and they'll be getting bigger and bigger in the weeks to come.

But at the moment....easy to miss!

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