The "F Fly"
Hook: Small dry fly hook
Thread: To match body
Body/Wing: Smallest CDC puffs you can find
Color: My go to color for thread and CDC puffs is black, though a do carry a few other colors
Note: What does the "F" stand for? Maybe Fish, Functional, Far-Out, Fantasticd, whatever you wish
CDC seems to be intended for dry flies. However, under water the do trap small bubbles of air that seem to give them extra life and attract fish
I fish this fly as the second fly trailing a small elk hair fly or Rainbow Warrior and a bit of weight. In rivers and streams where there are pocket waters, the weight allows the flies not not only get down where the fish are but to also stay in the pool longer to allow for more hookups.
I've had a lot of fun and success with this fly on Colorado streams and also Driftless streams.