Egg bands of the forest tent caterpillar, Malacosoma disstria Hübner, were sampled across a wide area of the Canadian prairie provinces during a large-scale outbreak in 1989 and 1990 to examine the incidence and distribution of egg parasitoids (Hymenoptera). Data on the parasitoid species found and the incidence and frequency of parasitism in three habitat types is presented. Three species of egg parasitoids were recovered, Telenomus clisiocampae Riley (Scelionidae), Ooencyrtus clisiocampae (Ashmead) (Encyrtidae), and Baryscapus malacosomae (Girault) (Eulophidae). Differences in the number of species occurring per egg band and the percent of parasitism were found among habitat types. These differences are correlated to the amount of spumaline cover on egg bands, which also varied among habitat types.