May 1—ST. MARIES — The most important part of tying a topwater bass fly is putting enough hair on the hook. So, one Saturday morning in early April, Derek Darst just kept adding more. He tied in clump after clump of deer hair, stacking three colors — green, gray and black. A pair of legs and a strand of monofilament, for a weed guard, dangled off the back of the hook. The hair filled the shank. It was a dense, spiky mess. Then Darst grabbed a double -edged razor blade and the wizardry began.