Rainbow Scud Dub: Hareline Dubbin, Inc works hard to dye and mix four different colors to make this particular fly-tying material - Scud Dub in Dark and Light Shade Rainbow. It is easy to dub and picks out perfectly for all your fly-tying scud and shrimp needs. It also helps to form the bodies of dry flies and gives nymph imitations the movement needed to attract fish.