San Juan worm
Hook: Scud, sizes 10-16 (here, a size 10)
Thread: 6/0, color to match body
Weight (optional): copper wire
Body: Ultra chenille
This pattern is great as a point fly in a two-fly nymphing rig. I like using the copper wire because it gives the fly a bit more weight to get down, and a little flash doesn't hurt.
Be sure to slightly singe the ends of the ultra chenille with a match or lighter. This cures the material and helps prevent it from unravelling.