This book was recommended to me by Joe Cornwall of Fly Fish Ohio and it has some very good information on crayfish. Ryan does a great job outlining some very detailed and well documented crayfish characteristics. The information is key to understanding what smallmouth bass look for when they hunt crayfish.
Prior to reading this book I tied my crayfish patterns large (size 2) and dark in color. Ryan discusses the fact that crayfish patterns should really resemble "softshell" crayfish which are much smaller and lighter in color. Studies have shown that crayfish in the 1"-2" range are all great, but 1 1/4" seems to be optimal.
Pincher's were another feature Ryan addressed in the book. Smallmouth bass prefer softer crayfish with smaller claws. The reasons are obvious....big claws are too much work!
If you are tying crayfish imitations make sure to read this book. There are a handful of crayfish patterns that look great, especially the one the author created.
After reading this book I am going to tie a handful of Mixed Medias (below) in size 4 and size 6!