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