The respective roles of stinging and envenomation by braconid wasps and of host acceptance and host suitability are not clearly associated. Two closely related species, Bracon brevicornis (Wesmael) and B. hebetor Say, show differences in their venoms and choices of Anagasta, Galleria, and Plodia as hosts. B. brevicornis discriminates between these 3 hosts much more than does B. hebetor, especially in stinging and in oviposition. Anagasta is much less sensitive to venoms of both wasps than Plodia and Galleria. While this possibly has a bearing on the poor acceptance of Anagasta by B. brevicornis, it does not with B. hebetor. Plodia is more sensitive than Galleria to venom of B. hebetor, but Galleria is more sensitive than Plodia to venom of B. brevicornis. Evaluation of the role of envenomation in the evolutionary adaptation of parasitoid to host will require a broad study.