This pattern is a slight variation on one of Earl Madsen's old AuSable (Michigan) River patterns. Earl was a guide in this area for many years and originated several patterns that are still widely used. This one, the hairy drake, is not well known. It is, however, the most effective fly I've ever used during a number of insect emergences including the famed Hexagenia Limbata hatch. Following is the pattern.
Hook: Togens nymph 2x long
Tail: Pheasant tail fibers
Body: Yellow poly yarn
Overlay: Deer hair
Rib: Grizzly hackle
Post: White deer hair
Hackle: Grizzly and brown mixed
Cover the hook from the eye to the bend with thread; tie in at the bend a clump of pheasant tail fibers, number according to fly size. Take thread 2/3 toward the eye and tie in poly yarn continuing thread back to the bend. Tie in at the bend the grizzly hackle rib. Take thread back to just short of the eye and wrap the yarn to this point and tie off. Take thread back to the 2/3 from the bend point and tie in a clump of deer hair long enough to extend beyond the bend of the hook. Secure it from there to the bend with successive thread wraps and bring the thread back to the 2/3 point in like manner. Now wrap the grizzly rib up to this point and tie off. Attach the post at this point being sure to cinch the thread in towards the butts of the deer hair overlay. Wrap the thread part way up the post, making a path on which to wrap the hackle. Tie in the hackles and start wrapping them from the top to the bottom over the path you just made. Tie off the hackle and whip finish the head.
This fly can be tied from #14 2x up to #6 2x to imitate our big mayflies in Northern Michigan. The combination of pheasant tail fibers and deer hair overlay well mimmicks a trailing shuck. I believe the fly also is taken for a floating nymph prior to releasing from the shuck. Tie it in a variety of colors to imitate whatever is on the water. Even large fish will take this fly without hesitation in the daylight.