The hornet (Vespa spp.) parasitoid Sphecophaga orientalis Donovan was imported into New Zealand from Israel as a possible 'new association' biological control agent for the adventive pestiferous social wasps Vespula germanica (F.) the German wasp, and V. vulgaris (L.) the common wasp. In quarantine, when adult wasps were absent, S. orientalis propagated prolifically on sealed brood of both species of wasp. In the field, parasitoid cocoons were formed in four of eight German wasp nests inoculated with the parasitoid, but there was no attack on 27 inoculated nests of the common wasp. Whether S. orientalis has established is unknown. If worker common wasps prevent attack or remove developing parasitoid larvae from cells, it is possible that parasitoids may be able to successfully attack the small nests constructed by queens in spring, before workers emerge. A major decline in wasp populations over the release period may have decreased the likelihood of establishment because of fewer small spring-founded nests available for attack. Animals and man; Control; Biological control; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Zoogeography; Dispersal; Means of dispersal; Land and freshwater zones; Australasian region; Palaearctic region Sphecophaga orientalis (Ichneumonidae); Control of; Vespula (Hymenoptera); Hymenopteran hosts; Vespula germanica & Vespula vulgaris; Parasite importation from Israel & field release for pest control; Introduction; New Zealand; Importation from Israel & field release for hymenopteran pest control; Israel; Importation into New Zealand & field release for hymenopteran pest control, review Vespula germanica; Vespula vulgaris (Vespidae ); Control by; Sphecophaga orientalis (Hymenoptera); Hymenopteran parasites; Sphecophaga orientalis; Parasite importation from Israel & field release for pest control; New Zealand; Hymenopteran parasite importation from Israel & field release for pest control; Israel; Hymenopteran parasite importation into New Zealand & field release for pest control, review none