Technical Abstract: Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae) is a solitary endoparasitoid of pestiferous noctuids. The effect of superparasitism on laboratory propagation of this species is not well known. Using sting frequency to manipulate superparasitism, I tested the hypothesis that a low level of self superparasitism (i. e., 2 to 3 parasitoid eggs per host) does not affect the production of female progeny. Young, presumably-mated, host-deprived C. marginiventris females were exposed to three Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) early instar larvae, one at a time, in Petri dish arenas, and observed as they stung these hosts once, twice, or thrice. The results indicated that approximately 90% of hosts (in all treatment groups) yielded a parasitoid mature larva, which spun a cocoon. An increase in sting frequency (from 1 to 3 stings per host) led to an increase of female progeny (from 8 to 43%) emerging from cocoons. Perhaps, inexperienced females primarily lay an unfertilized (= male) egg into the first host encountered. More fertilized (= female) eggs will be oviposited in subsequent hosts until the sex ratio of adult progeny falls within a range that typifies this species. This study has revealed that a S. exigua larva, subjected to a low level of superparasitism, can provide a suitable environment for the development of one C. marginiventris mature larva.