Fly Tying Video- Barr's Vis-a-Dun Baetis The Vis-a-Dun is a pattern designed by John Barr. This is our version of that fly. A great pattern for baetis and PMDs. Purchase materials to tie the Vis a Dun CDC Thorax Dun Fly Tying Materials Hook: Daiichi 1100 or Tiemco 100 Dry Fly Hook size 14-22 Thread: 70 Denier Ultra Thread Wing: Poly Yarn Dun or Light Gray Tail: Coq de Leon Fibers Abdomen: Nature's Spirit Fine Natural Dubbing Legs/Hackle: Dun Dry Fly Hackle Thorax: Nature's Spirit Fine Natural Dubbing Purchase materials to tie the Vis-a-Dun