This is a damsel nymph pattern originated by Doug Jorgensen.
Hook: Typical nymph (here, a size 12)
Thread: 6/0, olive
Wingcase: Olive duck or goose quill (here, goose)
Tail: Olive marabou
Abdomen: Olive Haretron dubbing
Thorax: Same as abdomen
Legs: Olive marabou
Most damsel nymphs are naturally one to one and a half inches, and the size 12 fits this nicely.