Janus,

Its the furry foam. I saw the gentleman tie this fly at the Midwest Fly Fishing show up in the Detroit area this year. I had had very few crawfish patterns in my box because Im picky about them. It seems that I only reserved for the more realistic type with lots of movement and this one fits the bill. I have only 3 different patterns in my box that do the trick for me.

Here is a link to the pattern and recipe:

http://www.hafft.ca/STEVEMAYFLIES.html

Seege