Recipe:

Tail: Med.-Dark Blue Dun Hackle fibers.
Wing: Mallard Flank (Wood duck can be substituted)
Body: Turkey Biot
Thorax: Muskrat Underfur
Hackle: Med.-Dark Blue Dun Hackle
Hook: TMC 102Y size 15-19

First gather your materials. Select a single hackle of the appropriate size. Use a saddle feather for nice hackle tails .

Using biots in fly-tying is hardly a new idea. Anyone that has seen a Kaufmann's stonefly is aware of their use as a tailing material. The goose biots used for tails and feelers on Kaufmann's stone are, however, the shorter goose biots. Select a primary flight feather from a turkey. These can be purchased from most fly tackle dealers, or you can dye your own. The natural barring on a wild turkey adds a neat effect. I often tie my smaller BWO's using a natural wild turkey biot. In any case the biots are the feathers on the barrow band of a primary feather (illustrated bellow)

The feathers come in pairs and the left and right side produce different texture bodies. For this pattern I use a right wing. Tear (do not cut) a single biot from the leading edge of the feather.

Select a mallard flank feather with fibers that are at least an inch and a half long. From a single feather, strip off the fluffy marabou like feathers on the lower stem. For each fly you plan on tying select exactly 6 individual fibers and tear them from the flank feather.

Note that a single biot will have a slightly darker line along its upper edge. Also note the slight concave of the biot. he biot should be moistened before tying in. Either store between two sheets of damp paper towels or place in your mouth.

Place the hook in the vise, and attach the thread. Yeah I know its simple step, but it always irks me when its left out of the instructions. So I include it. I prefer to attach the tails first, usually a clump of 5-10 fibers tied in at the bend. I also lay a wrap or two under the ails to splay the fibers a little and offer a slightly wider keel.

Lay the biot on top of the hook with the dark line towards you. The concave should cup over the hook shank. The biot should be wrapped around the hook shank towards the eye. You might want to give a slight twist on the first wrap to get it to lay just right. Each successive wrap should cover about half of the previous wrap. If you are off on the first or second wrap go back and reset the initial wrap. Bring the successive wraps forward to about 2/3 point on the hook. Note the ribbed effect of the biot. (If you use a left wing feather the ribbing is more subtle.)

Tye in the six flank fibers by the butts, so that they extend out toward the back of the hook also tie in the hackle feather as you would for a standard dry fly. Then dub a small amount-of muskrat to form the thorax.

Wrap the hackle as you would normally. Try to get 5 or six wraps onto the thorax. Don't crowd the eye. Use a bodkin to separate the six fibers into two groups of three fibers. (for really tiny flies this can be two clumps of two) Grab one of the clumps and form a loop over the hackle. Place two quick wraps of thread over the end. You can make the loops bigger by lifting up with the bodkin as shown. Or smaller by tugging lightly on the fiber ends. Do the same with the other clump of fibers. Whip finish and your done.