none The developmental history of Microplitis rufiventris Kokujev the parasite within singly parasitized hosts, Spodoptera littoralis (Boisduval), was compared with that in superparasitized hosts. Different levels of superparasitism had no effect on the length of the egg stage but caused changes in the lengths of the stadia of the surviving parasite and in the encpasulation ability of the host against the eliminated first-instar parasite. Larval development was faster in singly parasitized hosts and decreased with increasing superparasitism. The percentage of encapsulation of eliminated parasite larvae increased with increasing numbers of parasite progeny per host larva. The results suggest the existence of permanent and impermanent capsules, the latter detectable within heavily superparasitized hosts. Some of the surplus parasite progeny appear to be eliminated early by physiological suppression and others later by encapsulation. In singly parasitized hosts, a nontrivial number of parasite larvae died very early as a result of unspecified host immune response(s).