The western spruce bud worm,Choristoneura occidentalisFreeman, like its E counterpart, is host to many parasitoids. The composition of the complex differs. however, with space and time. The only published inventory of parasitoids of the budworm in the Colorado Rockies is by Dowden et al. (1948), who reared budworms and collected parasitoids during the final stages of an outbreak which ended in 1946–1947. A major budworm outbreak developed in the late 1950's, spread over most of the susceptible host type, and collapsed in the early 1960's, except in some areas where it still persists. During this period the parasitoids were studied to identify the species present and to evaluate their role in determining population trends (Dalleske 1963; McKnight 1971 a). This Note updates the earlier inventory.