The effects of temperature on emergence, development, oviposition, longevity and fecundity of <i>Cotesia orobenae</i> Forbes (Hymenoptera: Braconidae) were studied. Development time of parasitoid pupae decreased as temperature increased to 35°C. Temperatures between 20 and 25°C were most suitable for parasitoid development, oviposition and fecundity. Longevity was significantly affected by temperature, and was greatest between I5 and 20°C for both sexes. Sex ratios obtained from virgin females, females mated once and females exposed to multiple mating were compared. Virgin females produced only males, those with single or multiple mating produced more females than males. <i>Cotesia orobenae</i> exposed to five densities of third instar cross-striped cabbageworm, <i>Evergestis rimosaiis</i> (Guenee) (Lepidoptera: Pyralidae), for 24 h showed differences in percent parasitization among the treatments. The highest number of parasitoid cocoon masses was obtained from a density of 10 hosts. / Ph. D.