Black Fly Larva
Hook: TMC 3761 nymph hook 2X 16-20
Weight: Fine non-lead wire
Rear Body: Dark Olive Floss (wrapped over back half of body)
Front Body: Dark gray Muskrat (dubbed over the upper half of the hook shank)
Head: Black ostrich
- Wind lead on the front half of the hook shank and lacquer it.
- Wrap a piece of dark olive floss over the rear half of the hook; make a smooth taper. (Bowling pin shape)
- Dub dark gray muskat fur over the front half of the shank
- wind a head of black marabou fibers.
Gary’s log entry from Trout Flies Proven Patterns for the Blackfly Larva
Log Entry: April 9, 1990 Madison River
There are parts of the Madison that have heavy populations of blackfly larvae (Simuium tebersum, the common Buffalo Gnat). Why some patches do and other patches don’t is a mystery to me, but the distribution of these insects might be connected to seepage into the river.
My discovery of one of those sections, right below a high bank of weeping springs, was not due to any wonderful speculation. The trout were just fussy enough to make me curious. They snubbed most of my best flies, occasionally grabbing whatever happened to be on my line at the moment of clarity. It was a trout here and a trout there all morning, most fairly small, but finally one rainbow was large enough to safely stomach pump.
My samplings over the years have turned up plenty of blackfly larvae in fish, but except in small brooks, no trout has been crammed exclusively with them. This rainbow today was full of insects, the larvae taken from high in the gullet still alive and seemingly very grateful for release back into the water. A size 18 Blackfly Larva, and a leader with the last 12 inches whitened with a Mean Streak Marker, changed my dat around those springs. The small fly didn’t take a lot of monster fish, but it took the numbers. As usual with the white tippet, the trout hit the nymph harder than normal, too.
Downstream, away from the springs, the Blackfly Larva wasn’t nearly so spectacular, but it still fooled trout and whitefish as well as any other nymph. Two 17-inch rainbows hanging along a bank, one after another snatched the fly (but it would be wrong to characterize this in any way as a say for big fish – it seemed as if the 9- to 13-inch trout were feeling firskier in the chilly water).
In a few weeks when the bigger fish start to prowl, it might be wise to fit the Madison again. The will still want small flies, and the Blackfly Larva should be a good trick for finding feeding trout (it has always worked on rainbows).