Hatches Made Easy:
Black Caddis
1/28/08
(Reply to my email from Jason Robinson, Research Specialist III
UT Knoxville)
Hi James
13 species of Brachycentrus are known from North America. Of those 8
(perhaps 9) are known from the southeast. Aquatic insects of NC/SC lists these
species from the mountains of North and South Carolina (I'd wager all of them
are found in NC): adelus, chelatus, etowahensis, lateralis, nigrosoma,
numerosus, spinae. There may be at least one named since then I am not sure.
I have seen records from the Park of B appalachia, lateralis, nigrosoma and
spinae. Adults are distinguishable only by experts and microscopes, but the
larvae might be distinguished by the nekkid eye.
B nigrosoma has a fan-like arrangement of the setal fringe on the middle and
hind legs, other species have this setal fringe of appoximately uniform length.
B appalachia and lateralis are separated by the coloration of the mid and hind
tibiae and tarsi. In appalachia, the tibia is dark basally and is pale apically, tarsi
is dark. laterialis tibia is pale, with dorsal dark stripe, and tarsi pale. lateralis
has less striping on the head.
If the larvae has a plain colored head, or just a few spots, then it may be B
spinae or B chelatus. spinae has a rounder head, chelatus head is more
elongate with parallel sides.
If the head is patterned with yellow and dark marks or stripes, it could be
numerosus or spinae. Numerosus might have a cluster of yellow or pale spots
at the tip of the head, near the mouth. spinae is variable and can be difficult.
All of the species have microscopic characters that make the identification much
easier. See this paper for treatment of range, identification, ecology and
emergence times.
Oliver S Flint. 1984. The genus Brachycentrus in North America, with a
proposed phylogeny of the genera of Brachycentridae (Trichoptera).
Smithsonian Contributions to Zoology No 398. 58 p.
It's very likely on the internet for sale somewhere, I don't know. If you are into
brachycentrus then that's a good one to get.
Incidentally many little black caddis flying at brachycentrus time are probably not
brachycentrus.this year, on a trip to davidson river, we collected Rhyacophila
atrata, Rhyacophila minora, Lype diversa, Agapetus speces, Psilotreta species
and Goera fuscula. These looked like Brachycentrus to me in the field, and a
small 16 black dry fly would have done great I"m sure.
Brachycentrus adults often hang around bridge abutments and perch on the
walls. I'm sure they do the same under overhanging bushes and on logs in the
stream. If you collect the pupae, still in the case, you might be able to keep them
alive long enough to allow them to emerge. They need lots of oxygen.
Egg laying is probably done in masses, I can't remember. I do know that when I
collect Micrasema (another common caddis in the same family) the females
usually have big green balls of eggs on their abdomen, and they tend to lay
those all at once. I think Brachycentrus is the same way. I have seen very few
adults of Brachycentrus, but I did collect B nigrosoma at the Blue Ridge Parkway
bridge over the Swannanoa River in April 2006.
Great page!!!
Note:
We were on Davidson River around the first to middle of April, first good warm
day hatches. The information above about how to distinguish between larvae is
a bit rough and there would be nothing definite about that sort of identification.
If you really wish to know what you have you should consult a microscope and a
good reference guide.
jr
Copyright 2008 James Marsh