The influence of female body size and adult feeding on the fecundity and longevity of female Cephalonomia stephanoderis Betrem (Hymenoptera: Bethylidae), attacking the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae), was examined under laboratory conditions. Size and fecundity were positively correlated, whereas size had no influence on longevity of females continually provided with hosts. In contrast to theoretical models of host feeding, host feeding rate in C. stephanoderis increased over the parasitoid’s lifespan, whereas oviposition rate decreased with age. The oviposition rate was higher and the oviposition period longer in large females than in small ones. As C. stephanoderis grew older, egg and sperm exhaustion were observed, especially in small females where a single mating was not sufficient for fertilization of all the eggs deposited during their lifetime. Developmental mortality of the offspring of small females was higher compared with large females, which may be attributed to a greater ability of large females to subdue and parasitize coffee berry borer pupae. Host feeding, by itself, promoted female survival. All host stages enhanced wasp longevity, but eggs and pupae were the most effective host stages in increasing longevity. Our findings have significant implications in mass rearing and management programs by determining conditions likely to improve parasitoid production and defining desirable biological attributes of C. stephanoderis as a biological control agent of the coffee berry borer.