Q.
From WTDURYEA: While fishing the Upper Sacramento
(Calif), I stepped on what appeared to be a black
rock and ended up with 52 degree water running over
the top of my bib waders. On closer inspection, I
observed that the rock was covered with tiny black
worm-like creatures that seemed to curl up when
disturbed. They were attached by one end and resided
on a rock that was constantly wet but not entirely
submerged. Do you know what they are? I have not
seen any patterns that resemble these creatures, but
I can’t help but think they are a food source. I
tied some imitations and am anxious to give them a try.
A.
First of all, I’d be very hesitant (foolish?) trying
to identify an organism without actually seeing it,
but in your case, I’m pretty sure what you found.
It sounds like a classic description of a rock
covered with black fly larvae (Family Simuliidae).
The larvae can literally cover rocks having a thin
film of water going over them from which the larvae
filter out fine organic particles with basket-like
fans on their mouthparts. They are about a quarter
of an inch long, attached by anal hooks to a silken
pad they attach to the rock or vegetation surface,
and can let themselves into the water column and
then “reel” themselves back by a silk strand.
They appear as tiny “bowling pins,” with swollen
abdomens; older ecologists, like me, who remember
Lil Abner, liken them to schmoos. Trout do feed
on them.
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 December 29th, 2003 on Fly Anglers Online by Robert Younghanz.