The fly that you are going for sounds like a Callibaetis to me. Easy to find lots of pattern's for this mayfly. Here is one of the better one's By AL Troth. Ron

Gulper Special.

Hook- Any good dry fly hook such as Dai-Riki #320's Mustad #94840 Temico # 100's and so on

Thread- Brown 8/0

Tail- Grizzly Hackle fibers

Body- Dark Beaver fur

Wing- White Poly yarn

Hackle- Grizzly tied parachute style