Slide the Hareline Mottled Tactical Tungsten Bead Black onto a Tiemco 3761, start Veevus 12/0 black and run the thread back to where the bend starts, about level with the barb.
Prepare a brown hackle so the bare stem is about one shank-length long, trimming a little extra off one side so no barbules flare backward when wrapped. Tie it in at the rear with locking wraps and bind the stem forward along the side of the shank, then return to the tie-in point.
Tie in three strands of Peacock Herl together, tips trimmed for durability, binding them forward about a shank length; add clean-up wraps and bring the thread to the thorax, about one bead-width behind the bead. Take a couple of half hitches.
Spin the three herls into a rope and wrap forward in touching turns to the thorax, re-spinning as you go to keep it consistent; capture with thread and trim.
Palmer the hackle forward in five or six open turns over the herl, capture and trim.
Trim the hackle down, leaving some pieces sticking out for texture like case debris; use the bead to steady your hand and cut the rear a little shorter than the front for a slight taper.
Make a dubbing noodle of Superfine Dubbing White and wrap it as the rear of the collar, matching the density of the herl and hackle.
Wax the thread, noodle Ice Dub Peacock Black and wrap it right behind the bead for shimmer, then whip finish.
Other versions
6 more in the app: Classic Recipe, Fischer's Flies, Jig-hook cased caddis, size 16 (materials only), L'ami du moucheur, Fly Fish Food Tie, variant 1, Fly Fish Food Tie, variant 2.