Global FlyFisher. Fly from the pattern database -
All kinds of flies from all over the globe
The CDC & Elk family
The Polar Conehead
Read the article about the Susquehanna River
There are plenty of good crayfish patterns especially the Clouser and Whitlock flies. I keep my version very simple. For this fly, the "big fly for big bass" rule is the exception. A small crayfish (2 inches or less) with small pinchers is preferable to a larger imitation. Brown over orange and olive over yellow are two good color cominations.