none Laboratory studies were undertaken to investigate host preferences and host sensitivity to venom of the ectolarval parasitoid, B. brevicornis (Wesmael), as indicated by numbers of fully paralyzed host larvae during a limited period. Larvae of Sesamia cretica (Led.)) were used in all traits. When 5 host species (Galleria (G. mellonella L.), Ephestia (E. cautella Walk) Sesamia, Spodoptera (S. littoralis (Boisd.)) and Ostrinia (O. nubilalis Hb.)) exposed to the parasitoid separately, Galleria was significantly the most sensitive, with Ephestia the least susceptible. When 3 host species (Spodoptera, Sesamia and Ostrinia) were accessible to the parasitoid in close confinement, Spodoptera was significantly the most preferred with Ostrinia the least. When 2 borers (Sesamia and Ostrinia) were exposed jointly, Sesamia was significantly more favored than Ostrinia. When 2 hosts (Sesamia and Spodoptera) were exposed in combination, Spodoptera was favored. Wasp venom is known to be effective in 24 hosts. Time required for full paralysis varied significantly among different species of larvae.