This is the perfect wool for the killer bug classic Grayling pattern from nymph expert and legendary river keeper Frank Sawyer. This fly pattern still doesnt disappoint, but if you follow Sawyers tying instruction, the killer or (grayling) bug as it was originally named, could and should only be tied with one brand and shade of wool, Chadwicks No. 477. At Semperfli we have a card of the original Chadwicks 477 which we used a blend of wools to match dry and particularly wet with our substitute as we developed it. Now this is one of the most accurate Chadwicks 477 substitutes available. Remember the Killer bug pattern that may be one of the most simple flies ever tied, tie it with Semperfli Chadwicks 477 Substitute!