The answer is simple: if there is plenty of open water, brookies in tiny creeks will eat at the surface. If you can fish the water successfully with a nymph, a dry will work just as well. The secret is that fish in small freestone streams are almost always hungry, and they will get a meal whenever they can. That means they will take small flies when a hatch is on, and big flashy ones when they can fit them in their mouth. Don't hold this rule to me, nymphing and using wets is much more productive in the winter, but there will always be a little blue line with brook trout willing to eat dries. I demonstrated such this winter by catching at least one trout on a fly fished dry each month I was able to fish. I landed many on wet flies skated on the surface in December (that counts, right? ) and managed a few on Bombers in January. In early February I caught brookies on a Royal Wulff. These outings kept me from getting really bad cabin fever that I typically experienced in the past, when I thought winter was not the time to be fishing.