Monday, May 21, 2012

Moving into Leuctrid (Rolled-winged stonefly) Season

Last week when I picked up the Alloperla Chloroperlids (genus Alloperla, Green stoneflies) in Sugar Hollow, I was sure I had picked up some Leuctrids: today I went looking for more Alloperlas -- and thought that I had them -- they all turned out to be Leuctrids!!!  (Both nymphs have long, thin, abdomens that are essentially parallel sided.)

But we're moving into their season and can expect to see more and more nymphs, some might be fully mature.  I found this one today -- badly mangled -- but you can see how the wing pads had already turned black.

Beaty reports that there are three genera of Rolled-winged stoneflies found in his state -- Leuctra, Megaleuctra, and Paraleuctra --but by far, the most common is Leuctra (Beaty, "The Plecoptera of North Carolina," p. 2).  In central Virginia, Leuctra is the only genus to date that I've seen.  They are easily ID'd -- well, using a microscope that is -- by the fact that the labial palps extend past the rest of the labium.  (Sorry, thought I had a photo of that -- but I'll take one next time around).

The sun was again giving me fits today when I was trying to get my photos.  Still, I managed a few nice photos of one of these nymphs.

Our Leuctrid nymphs are now large enough that their characteristic wing pads are easy to see: both front and rear wing pads are "finger-like," and the front wing pads are wider than the abdomen, while the rear pads lie on top of the first abdominal segments.

Beaty says that some Lecutrids are found in "larger rivers": I've only seen them in very small streams.

Not much else to report on today -- it was a very quick trip since there were threatening skies.  But I did find plenty of the "other" nymphs that have moved into their season as well: the Perlodid stoneflies, Remenus Bilobatus and Isoperla holochlora.

R. bilobatus

I. holochlora

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