Not a direct answer to the question, but may be part of the solution. When the bite moves above surface with damsels, the volume can make it really tough at times to draw much attention. I consider an adult, or any similar dry fly, to be a third of my options; the other two being small emerger and simply staying subsurface (damsel nymph, leech, etc). Most often I'll find best success below the surface.
One other tactic, try also moving into the looser, less dense food and feeding. Like minnows, damsels are just too concentrated a lot of times.