This pattern is in George Grant’s book “Montana Trout Flies”, published in the early 70’s.
It is attributed to an unknown “amateur flytier from the Bozeman area”. It is similar to Dan Bailey’s “Yellow-Bodied Gray-back”.
TaB,
You made me go back and tie my version of one of Jack Horner’s Goofus Bug.
It has been years, and I guess it shows. Not the best attempt, but it might work.