Who knows what a fish that reacts by instinct, takes a fly as representing?..often times we know during a hatch, but fly anglers want to attribute the take to something specific as to why the fish ate the fly. I think often, it is just a buggy looking offering, and they are opportunistic. The Woolly Bugger is a great example. When the marabou tail was substituted for the red, hackle fibers on the Woolly Worm, the fly angler hierarchy anyway, attributed the motion of the marabou as being that of a leach. The woolly bugger, in different colors, has worked for steelhead, salmon, pan fish, you name it. It is the motion of the marabou, rather than appearing to be a leach, IMO. Wet flies went out of favor because the entomology thinking fly angler couldn't attribute a wet fly as representing anything once understanding the stages of bug emergence. My soft hackles fell out of favor, and were replaced with more exact replicas of the stages of emergence. Soft hackles are back along with the wet flies...it is the motion, and suggestion of life that attracts a fish.