Here is the fly pattern sheet for the Dark Hendrickson mayfly.
Materials
Hook:
Daiichi 1180, #12 – 18
Thread:
8/0 gray
Wing:
Wood Duck flank upright divided
Tail:
Medium blue dun hackle fibers
Body
Muskrat
Hackle:
Barred dun
For more information about the fly, see my Throw Back Thursday Fly post – Dark Hendrickson.