Depth Charge Caddis

At the extreme parts of the season the Grayling are huddled in deep holes and refuse to budge. They are still eating though, and can be persuaded to accept a your fly, if it is presented at their level. This heavy monstrosity (slightly bigger and heavier than a rimfire bullet) will do the trick, just remember to keep the bead away from your graphite rod (and don't you ever dare to tie it on a bamboo rod setup, that would be extremely bad manners!).

The tie:
#10 Jig hook
4.6mm Tungsten bead
a layer of flat lead
green UNI Neon thread for the peeping head
a turn of Partridge hackle
natural spiky hare ribbed with gold tinsel