Smernsky,
I had the same problem on Spruce Creek in Central Pa. several years back. As a guest at the Spruce Creek Rod and Gun Club I had only a limited amount of time on the stream. And it was full of big educated fish. I prepared for my trip by looking up that stream in Charley Meek's "Pennsylvania Trout Streams and their Hatches" for the month I would be fishing there. The book called for #22-28 black trico's. I had never tied that small before and had to get a magnifier light. I tied a half dozen of the described fly. On the stream I saw monster (18" to 24") trout rising to pellets and my other dry fly offerings. But no takes and no rises after one or two looks. I finally tied on one of those #22 black tricos and WHAM! They saved my trip!
So check out the book! I have found it to be relatively accurate on most streams with only weekly variations for yearly weather changes! Ron G.