Start the black thread and run it back to the bend.
Snip a small tuft of yellow calftail, not too sparse since this is a fuzzy fly, and bind it in at the bend as a tail just short of a shank length. Bind the butts forward with loose open wraps to bulk out the underbody and snip any excess.
Return the thread to the tail and bind in the black tinsel.
Bind in the cactus chenille at the same point, then advance the thread to the front where the hackle will go.
Rough up the chenille fibers, then wrap it forward with each turn tight against the last so the chenille core lays down a solid green underbody. Tie off near the eye and snip.
Counter-wrap the black tinsel forward in three to four turns and tie off; the last turn will be hidden by the hackle.
Bind in the olive soft hackle, snip the excess stem, and take one wrap without pliers; pinch the fibers back with a finger for the second wrap. That is plenty. Tie off.
Sweep everything back, build a decent-sized nymph head, whip finish, and snip off the leftover feather tip.