What it is
Hareline UV2 Sparkle Yarn is a synthetic sparkle yarn that’s UV2 double-dyed to boost UV fluorescence. It has a crinkled texture with a natural sheen that refracts light, so it reads like the reflective, “alive” look you see on real insects in the film.
What to tie with it
Use it for tailing shucks on emergers and for tails and shucks on nymphs and dry flies, usually by tying in a sparse strand or two and trimming to length. It also works for nymph wingcases and for a range of dry-fly wing and visibility jobs like loop wings, parachute posts, spinner wings, and downwing caddis and stonefly wings.
Flies and the fish they're for
LaFontaine’s Sparkle Pupa is the classic pattern built around this yarn to suggest the airy, reflective look of a caddis pupa as it rises. Fish it for trout in rivers and tailwaters during caddis activity, especially when pupae are ascending and emergers are getting eaten in the film.
How it compares
Compared with Hareline Antron, UV2 Sparkle Yarn refracts light more and has the added UV2 double-dye for stronger UV effect. Antron is more subtle and doesn’t have the UV2 treatment.
