In that article I suggested that you look for a trout chasing a mayfly, cast a White Fly with over-sized hackle just upriver from the riser, and start dragging the fly. Light brown hackle fibers. Cream or tan angora. Pale gray poly yarn. Females mate, lay eggs on the surface, and die on the surface.
Few anglers realize the value of an emerger pattern just before and during the hatch.
My son, Bryan, and I conducted an experiment on the Yellow Breeches several years ago. We tied a two-foot 4X tippet to the bend of the hook of the dry fly and attached an emerger pattern to it. We then counted the number of trout that took the dry compared to the number we caught on the emerger. In two hours of fishing we caught 14 trout on the tandem. Two of these trout took the dry fly and 12 took the emerger.