What it is Hareline UV2 Select CDC is cul de canard feathers that have been treated with a UV2 double-dye process. CDC fibers trap air and stay naturally buoyant, so they want to ride high and look alive in the surface film. The UV2 treatment adds UV fluorescence and UV reflectivity without making the feather fussy to handle at the vise. What to tie with it Use it anywhere you want a soft, breathing feather that will still help the fly float: tie it in as emerger and dry-fly wings, either as a small bunch, a swept-back wing, or a simple looped-in tuft. On nymphs, it works well as a collar you can wrap like a hackle or as short legs picked out from a turn or two at the front. It’s an easy material to pinch, measure, and secure without fighting stiff stems. Flies and the fish they're for CDC is a go-to wing and collar material for mayfly, caddis, and midge imitations that get fished to selective trout in rivers and spring creeks, especially when fish are feeding in the film. In stillwaters it also shows up on small emergers for cruising trout that key on midges and mayflies just under or in the surface. Because you can use it for both dry-fly wings and nymph collars/legs, it covers the hatch from the underwater stage to the adult on top.
