One of our favorite bugs that can be fished year around the Blue Wing Olive (BWO) dominates our waters in the southeast and pretty much everywhere across the US. Those little grey water skippers you usually see are BWO's especially if it's overcast or raining. Between this BWO, a Caddis, and a Stinger Soft Hackle you can't go wrong on just about any watershed.
We highly recommend silver, then gold, then copper. #20 is a solid choice, but #18 ain't too bad either. Siman Peacock Fine Dubbing in Blue is tops.
This bug has caught really big to little bitty trout of all species. Get you some!