Three species of predators and parasites were found associated with western spruce budworm (Choristoneura occidentalis Freeman) (Lepidoptera, Tortricidae) in Larimer Co., Colorado. These were: Ancistrocerus antilope (Panzer) (Hymenoptera, Vespidae), Goniozus gracilicornis (Kieffer) (Hymenoptera, Bethylidae), and Ceromasia auricaudata Townsend (Diptera, Tachinidae). The first two species stored caterpillars in wooden trap nests, while the third was reared from final instar budworms.
Evans, Howard E.
"Observations on natural enemies of western spruce budworm (Choristoneura occidentalis Freeman) (Lepidoptera, Tortricidae) in the Rocky Mountain area,"
Great Basin Naturalist: Vol. 47
, Article 19.
Available at: http://scholarsarchive.byu.edu/gbn/vol47/iss2/19