Q.
We recently fished a northern Va stream for trout
in Hot Springs (The Homestead), and caught many
natives, rainbows, and browns. We kept a couple
rainbows for the table and upon cleaning them we
realized that they were eating a hard, small type
of snail looking thing that was attached to the
rocks in the area. All the fish were thin but
very healthy and active. What are these snail
cone looking things and do trout normally eat
them? Thank You.
A.
It sounds very much like the trout were feeding
on a small, cased caddisfly larva of the genus
Helicopsyche. It constructs its
case from sand grains or rock fragments and builds
it in a coiled spiral that resembles a snail shell.
In fact, it was mistaken for a snail for sometime
until someone looked at it closely and discovered
that it was a caddisfly, not a mollusk.
Helicopsyche is the only genus of the
family Helicopsychidae that occurs in North America.
Trout readily feed on these and other cased caddisfly
larvae.
To be doubly sure, I contacted two colleagues at
Virginia Tech to verify that this organism is present
in VA streams; one verified that it occurs throughout
western VA so is probably also in the northern part
of the state. The second said that he has also found
trout gorged on true snails, but from your description
it doesn’t sound like they are molluscs.
If you have a question, please feel free to contact me.
~ C. E. (Bert) Cushing, aka Streamdoctor
105 W. Cherokee Dr.
Estes Park, CO 80517
Phone: 970-577-1584
Email: streamdoctor@aol.com
The ‘Stream Doctor’ is a retired professional stream ecologist and
author, now living in the West and spending way too much time
fly-fishing. You are invited to submit questions relating to
anything stream related directly to him for use in this Q & A Feature
at streamdoctor@aol.com.
Originally published August 30th, 2004 on Fly Anglers Online by Robert Younghanz.