Thursday, February 14, 2013

Doubling up on Caddisflies: Back to Sugar Hollow

Another "rare" day of sunshine, so this morning I headed off to my favorite small mountain stream in Sugar Hollow.  Lots of insects.  But I seemed to score best with the caddisfly larvae.

In the photos above, a pair of free-living caddisfly larvae, Rhyacophila nigrita.  It's one of the species I commonly find in this stream.  Sometimes the body is white; sometimes -- as here -- it's aquamarine.  R. nigrita is described by Beaty in the following way:

R. nigrita -- head black or brown and parallel sided; pronotum darker anteriorly. Occurs mostly in small Mountain streams.  Third most common Rhyacophila in NC.  ("The Trichoptera of North Carolina," p. 61)

The Appalachian mountains, by the way, are rich in Rhyacophilids, and the R. invaria group -- which includes R. nigrita -- is the subject of a very important study: Aysha Lynn Prather and John Chapman Morse, "Eastern Nearctic Rhyacophila Species, with Revision of the Rhyacophila invaria Group," Transactions of the American Entomological Society 127 (1): 2001, pp. 85-164.  They note that the 14 species of the R. invaria Group are "endemic to the Appalachian Range." (p. 86).

But another double shows up in my photos -- the common netspinners that we find in these small mountain streams in the spring, Diplectrona modesta.   D. modesta and D. metaqui are both attested in North Carolina.  Both have a "submedial dark U-shaped pattern" on the frontoclypeus, and a "dark pattern posterior to and along the frontoclypeal sutures." (Beaty, "The Trichoptera of North Carolina," p. 74)  But they differ in one respect: there is an asymmetrical notch in the anterior margin of the head on D. metqui, but not on D. modesta.  These are D. modesta.

And a couple more photos.


I also doubled up on Uenoids today.  I found two different species in the very same part of the stream: Neophylax consimilis and Neophylax mitchelli.  Remember that N. consimilis has a pale area or stripe on the head, while N. mitchelli is distinguished by a long, pointed tubercle on the head.  Both have "well developed clavate ventral gills on abdominal segment 1." (Beaty, "The Trichoptera of North Carolina," pp. 86-87.)

Neophylax consimilis:

Neophylax mitchelli -- pictures of three different larvae.



#3 (very small)


Other findings and photos.

1. A fairly big Limnephilid caddisfly larva (case about 1 inch long), Pycnopsyche gentilis, the one that makes the three-sided case out of sections of leaves.  (The "cling-ons" are a mature large winter stonefly, T. atlanticum, a tiny E. invaria spiny crawler, and one of the D. modesta netspinners.)

2. Perlodid stonefly, Malirekus hastatus.  I found two -- neither one is mature.  (Their heads are too big for their bodies.)

3. Flatheaded mayfly, Epeorus pleuralis.  Lots of them on the bottoms of rocks.

4. And a Chloroperlid stonefly (green stonefly).  This is the most common taxon I saw today.  Unfortunately, I discovered that the M. hastatus Perlodids like to eat them!


Sugar Hollow: a small mountain stream in the winter.

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