Rear gaster Black dry-fly dubbing (or black tying thread built up) (small ball)
Hackle Black or dark dun cock hackle (1 feather, 2-3 turns)
Front thorax Black dry-fly dubbing (small ball)
How to tie it
Start the thread at the bend and dub a distinct shiny black ball for the rear gaster over the rear third of the shank, the pinched waist between two bumps is what makes it read as an ant.
At the mid-point tie in the black hackle by its butt.
Take 2-3 turns of hackle to form the legs at the waist, then secure and clip the surplus.
Dub a second, slightly smaller black ball in front of the hackle for the head/thorax.
Whip finish at the eye and add a tiny drop of head cement. For a low-riding version, trim the hackle flat underneath.