For smallmouth, trout and carp, it pays to have a small selection of crayfish imitations. Flay's Cray is an easy tie with the profile, color and flash to attract the attention of a predator. I like that it uses a red tag as a strike trigger.
A crawdad pattern is worthless unless it is weighted to sink right to the bottom. When plumbing the depths for trout or smallmouth bass, fish these imitations like any other streamer with long strips and long pauses.
Tie this pattern with brown thread on a No. 2 4x long streamer hook. Start with 10 or more wraps of .025 lead wire. At the back of the hook, wrap a red wool tag and then tie in split squirrel tail fibers dyed rust. Tie in orange or black rubber nymph legs for antennae and six strands of copper Krystal Flash — three on each side. Wrap the body with peacock sparkle chenille and overlay with rusty brown dubbing. Tie in large dumbbell eyes and finish with a few turns of olive dubbing.
— Gary Lewis, For The Bulletin