Friday, December 19, 2014

The "odd" Lepidostomatid: back to Sugar Hollow's small streams

What's wrong with this picture?  Well, that appears to be a Lepidostomatid (genus Lepidostoma) larva in a 3-sided case made of pieces of leaves, and as Wiggins has told us, Lepidostomatid cases "are usually four-sided and constructed of quadrate pieces of bark or leaf." (Glenn B. Wiggins, Larvae of the North American Caddisfly Genera, 1977 [1st edition], p. 156)  They can also, when very young, make cases out of sand grains, and we also find cases that combine the two construction techniques.  So,  we find these

and these

and these

What does make a 3-sided case out of pieces of leaves or bark?  The Northern case-maker, Pycnopsyche gentilis.  This one

Our Lepidostomatid is in the wrong kind of case.  I'm not sure what to make of this find: it could be a matter of species.  Wiggins adds "Final instars in some...species assigned to Lepidostoma have cases of plant materials placed spirally or transversely" (p. 156) so there may be some odd cases around.  In any event, This larva cooperated for some very nice photos, despite it's very small size (about 5 mm).

By the way, I did find other 3-sided cases this morning that did contain P. gentilis larva.  This case for example.

I kept both of the cases you see in these photos, and here's what I found when I looked into my microscope tray.

Very curious!

I spent the morning at the small stream in Sugar Hollow that runs through a friend's land high above the Moormans.

 The water was low, but we had no trouble finding interesting insects.  Some other photos to look at.

1. Perlodid stonefly, Malirekus hastatus.  This is a "killer," and this one ate one of my Roach-like stoneflies the moment I glanced away?

2. Roach-like stonefly, genus Peltoperla.  Only saw three or four.

3. A "Weighted-case maker": Goera calcarata.  Beautiful case.

4. And last but not least, a "normal" Lepidostomatid in a case made of sand: one of the smallest I've ever seen.


Back up here in the winter -- but we'll be needing some rain.


Postscript:  On reflection-- I suspect that our "odd" Lepidostomatid had simply moved into a P. gentilis case that had been abandoned.  It happens.  Seems the most likely explanation.

No comments:

Post a Comment