Semperfli Chadwicks 477 Substitute Wool is the perfect wool for the classic Killer Bug Grayling pattern from nymph expert and legendary river keeper Frank Sawyer. This fly pattern still doesn’t disappoint, but if you follow Sawyer’s 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, Chadwick’s No 477.
 
Semperfli have a card of the original Chadwicks 477 and they used a blend of wools to match dry, and particularly wet, with their substitute as they developed it.  Now this is one of the most accurate Chadwicks 477 substitutes available.
 
Remember the Killer Bug pattern may be one of the most simple flies ever tied,  so tie it with Semperfli Chadwicks 477 Substitute!