Hook Standard nymph hook with bead, 14-22, matched to the naturals
Thread Tan/cream body, black rib 8/0 body; Uni 6/0-8/0 black for the rib
Materials
Bead Glass, brass, copper, tungsten, or tin. By sink rate (One)
CDC puff Natural dun cdc feather (One, trimmed, for the gills)
Uni-Thread Black thread (One length as ribbing)
Peacock herl Natural peacock herl (1-2 strands for the collar/thorax)
How to tie it
With the bead pushed back on the shank, start the thread in front of the bead right at the eye.
Trim a CDC puff down to size and tie it in at the head so it protrudes forward off the eye. These are the gills; cover the butts, then whip finish and cut the thread.
Slide the bead forward over the tie-down so it seats behind the gills; check that the eye is still reachable under the CDC.
Reattach the tan/cream thread behind the bead and begin tapering a thread body rearward. The body is built in about four passes of flat thread.
On the second pass, tie in a length of black Uni-Thread at the rear for the rib and continue smoothing the body forward.
Complete passes three and four, finishing with a slender taper that locks the bead in place from behind.
Cross-wrap the black thread forward in open spirals as the ribbing and tie it off behind the bead; trim.
Tie in peacock herl and take a couple of wraps as a collar to build a bit of thorax behind the bead.
Whip finish behind the bead, then trim the CDC gills down slightly if they're long.