Head cement (brush-in-cap or flex cement) (Over shellback and tie-off)
How to tie it
Start the thread and dress the shank, then dub a body of brown olive Ice Dub the length of the shank.
Clean and stack a bunch of bleached elk hair. Measure it against the hook from front to back so that, once folded, the tips will make a tail just under a gap-width long. Tie it in at the front with the tips forward, a soft turn or two first, then firm pressure; cut the butts off at a good angle.
Tie in a ginger hackle at the front with the butts trimmed close, then run the thread and hackle together to the rear in one pass, the thread tracking alongside to reinforce the stem. Tie the hackle off at the bend and break off the tip.
Give the hackle a light clip along the top of the body only, so the shellback can lie flat.
Pull the elk hair back tight over the top as a full shellback and tie it down at the bend, leaving the short tips as the tail. Whip finish at the rear (an extended-reach whip finisher helps).
Coat the rear tie-off and hair with head cement or clear flex cement. This fly catches enough fish that the hair needs the reinforcement.
Lay the scissors along each side and trim the hackle so fibers come only off the bottom like legs. Side-sticking hackle makes the fly track crooked, and fussy fish will go dead on it.