Hook: TMC 105 glo-bug, size 6. (Scud hooks or Mustad caddis/shrimp hooks also work well).
Body: Brite Blend Red dubbing mix by Spirit River.
Tail: Flame red marabou, (spikey feather tip stuff).
Start by tying in a SPARSE tail of red marabou fibers approximately 1/2 to 3/4 of an inch long. Tie the tail so it is coming off the hook just past where the shank starts to bend. This gives the tail a slight angle with respect to the hook shank and an overall "bent" look to the fly.
Next dub a sparse, tapered body using the Brite Blend mix. Start out dubbing slightly thicker at the base of the tail (head of the krill) and taper out evenly to the eye of the hook and whip finish.
Last step is to carefully pick out some "legs". The dubbing mix has thin mylar filaments that work well for this. Pick out legs on the side facing the hook point and pick out more towards the tail. This gives the fly a real "shrimpy" look.
Note: the "tail" actually simulates the antennae, so the "head" would be at the base of the tail, not the eye of the hook.