I tie up several different size crayfish patterns using gray squirrel tail for the pinchers. They work great and are real simple patterns.

Hook: 6x long sizes of choice
Thread: tan 6/0
Under body: Lead wire or substitute
Pinchers: Gray squirrel tail
Body: tan chenille
Carapace: Mottled Turkey
You can also use olive as your color or just match the color of your local crayfish.

Skin out the squirrel and use a mixture of salt and borax dry laundry soap. Just rub it on the flesh side and let it cure for a couple of days, and you'll have a squirrel skin to use for what ever you want. The back of the squirrel can be shaved with a set of eletric clippers and put in a coffee grinder or blender to make squirrel dubbing. Mix the fur with a little antron yarn or poly yarn before blending, this will give it a little sparkle. Squirrel tail is very hard to dye, so unless you realy know how to do it I wouldn't suggest trying. Normal dyes such as Ritz won't work most of the time, you need commercial grade dyes. Wtih that being said, natural squirrel ( red or gray) can be used in just about any fly pattern out there. Good luck,Dave