Frank Sawyer used Chadwicks 477 yarn for his Killer Bug, which is no longer available. The Oyster colored yarn is the closest to his original yarn.
Killer Bug
Utah Killer Bug Flies (12 pack) — DRAGONtail Tenkara
The yarn used by Tenkara Guides in Utah to make their Utah Killer Bug flies that are very productive. This yarn has also been used by many Tenkara
Killer Bug Yarn (oyster)
Teton Tenkara: Variations on a Bug
Semperfli Perfect Shrimp Wool Yarn — DRAGONtail Tenkara
Stewart's Killer Bug Trout Fly
Killer Bug Yarn (oyster) — DRAGONtail Tenkara
Killer Bug Yarn (oyster) — DRAGONtail Tenkara
Utah Killer Bug Flies (12 pack) — DRAGONtail Tenkara