Four cereal stemborers occurring in Kenya,Chilo partellus(Swinhoe),Chilo orichalcociliellusStrand (Lepidoptera:Pyralidae),Busseola fusca(Fuller), andSesamia calamistisHampson (Lepidoptera: Noctuidae),were exposed to females of the larval endoparasitoidsCotesia flavipesCameron andCotesia sesamiae(Cameron) to assess their acceptability for oviposition and suitability for development of the parasitoids. There was no difference in the acceptability of the 4 hosts exposed toCotesia flavipes. In contrast,Cotesia sesamiaepreferredS. calamistislarvae, followed by the 2 Chilo species;B. fuscalarvae were the least attacked byCotesia sesamiae. The suitability of the 4 hosts also varied with the parasitoid species. Neither parasitoid species developedinB. fuscaand egg encapsulation was observed. BothChilospecies andS. calamistiswere suitable hosts for the development ofCotesia flavipes. However, higher immature mortality was observed inS. calamististhan inChilo partellus. There were no differences in the mean number of progeny per female or the sex ratio. The most suitable host forCotesia sesamiaewasS. calamistis, followed by the 2Chilospecies which were equally suitable. When 3rd, 4th, 5th, and 6th instars ofChilo partelluswere exposed toCotesia flavipesfemales, immature parasitoid mortalitywas highest in 3rd-instar hosts.