At Ottawa, during studies on the parasites of the armyworm, Pseudaletia unipuncta (Haw.), in 1955, 1957, and 1958, 20 species of Hymenoptera were reared from larvae or pupae of the armyworm collected from fields in the area during July and August. Of the 15 species thus far identified, 12 were primary parasites; four of these, namely, Euplectrus mellipes Prov. (Eulophidae), Hyposoter annulipes (Cress.) (Ichneumonidae), Microgaster auripes Prov. (Braconidae), and Therion sassacus Vier. (Ichneumonidae), have not been previously recorded as parasites of P. unipuncta.