Please keep us posted, if you ever get them to hit on the surface. I remember catching a few accidentally - on medium sized deer hair bugs I was using for Smalllies. They did seem to like a mouth full. Also - if you are ever inclined to use bait, they love a peeled crayfish tail. We would catch small and medium sized crayfish and break the tails off and peel them, and put them on a hook and float it into the hole - and wham - instant hook up. I know you are a fly fisherman but just thought I would toss that out - in case. I enjoyed fly fishing too - but we learned to use all the methods and they all had their time and place.