I never questioned the effectiveness of the pattern. It is outstanding. It's fun to tie and especially fun to fish because it is so good. I tie and fish them with both the deer hair wing and, in the smaller sizes, a CDC wing. I'm going to try Davie McPhail's pattern with both materials in the wing. I was just curious as to a part of the fly that didn't seem to add anything to it, but the suggestions of visibility and ease of tying answer my question. Thanks!

Joe