none Field populations of Mythimna separata and its parasitoid, Cotesia ruficrus , were sampled from maize over two successive seasons. Populations of M. separata larvae (up to 1.5 larvae per plant) were detected in February of both years. Larvae were heavily parasitised by C. ruficrus which caused mortality of up to 98%. Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Host parasite relationships; Ecology; Population dynamics; Land and freshwater zones; Australasian region Mythimna separata (Noctuidae); Hymenopteran parasites; Cotesia ruficrus & Eupteromalus; Parasitism & hyperparasitism impact on populations; Hyperparasitism; Cotesia & Eupteromalus (Hymenoptera) seasonal prevalence; Prevalence; Seasonal; Cotesia & Eupteromalus (Hymenoptera) parasite & hyperparasite; Reaction of host to parasite; Mortality related to hymenopteran parasite & hyperparasite; Mortality; Hymenopteran parasites & hyperparasites impact; Seasonal abundance; Hymenopteran parasite & hyperparasite influences; New Zealand; South Auckland; Pukekohe; Hymenopteran parasite & hyperparasite ecological impact Cotesia ruficrus (Braconidae); Hymenopteran parasites; Eupteromalus; Hyperparasitism in lepidopteran host; Lepidopteran hosts; Mythimna separata; Parasitism & Eupteromalus hyperparasitism effects on host ecology; Prevalence; Mythimna (Lepidoptera) host mortality relations; Interactions with Eupteromalus hyperparasite; Reaction of host to parasite; Mythimna (Lepidoptera) mortality; New Zealand; South Auckland; Pukekohe; Parasitism & hyperparasitism effects on lepidopteran host Eupteromalus (Pteromalidae); Hymenopteran hosts; Cotesia ruficrus; Hyperparasitism in lepidopteran host; Hyperparasitism; Parasitism of Cotesia on Mythimna (Lepidoptera) host; New Zealand; South Auckland; Pukekohe; Parasitism & hyperparasitism effects on lepidopteran host