The Comparadun is one of the most universally effective fly designs for matching mayfly hatches. Because there is no hackle, the body of this fly rides flush against the water; it presents a well-defined profile of both body and wing and makes an excellent flat-water pattern. Yet the deer-hair wing gives this fly good buoyancy, and it can hold its own in the rougher stuff. If rising trout refuse this fly, you can trim the wing to a stub and fish the pattern in the surface film-it makes a highly credible emerger.