Olive Bloa
Hook: Sprite Perfect #14 (or equivalent)
Thread: Gudebrod 8/0, olive
Hackle: Hen, dyed olive
Body: Heron barbs, dyed olive (or substitute). An alternative body is greenish yellow silk with a light dubbing of olive seal's fur.
Rib: Tying thread

Excerpt from The Art of the Wet Fly - W.S. Roger Fogg (1979):
An excellent all-rounder and much favoured during the last century by John Jackson and T.E. Pritt. It may be dressed to suggest nymph, emerger or floating dun (if a cock hackle is employed).

Cheers,
Hans W