Friday, January 6, 2012
Rhyacophila fuscula: an Early Instar
I now have it on good authority -- Steven Beaty (NCDWQ) -- that this odd looking freeliving caddisfly larva I found yesterday is probably an early instar of the species Rhyacophila fuscula -- which is the most common freeliving larva we find in our streams. This one:
One of the distinguishing features of R. fuscula is the dark, "top-less H" pattern on top of the head. This:
And clearly that's missing in the larva I found. But that's probably because the head has not yet darkened in color, nor has the "H" yet developed. What's critical is that the anal prolegs on this nymph are clearly those of R. fuscula which have 1) "apicolateral spurs" (pointed out in the photo below), and 2) anal claws that are dentate -- i.e. they have teeth. These are clear in these microscope photos.
So there you go. A good lesson to learn -- always need to use those microscopes and check things with care.