The biological characteristics of the ectoparasitoid Catolaccus grandis (Burks) were evaluated after 1, 2, 5, and 10 generations of in vitro-rearing and compared to parasitoids reared in boll weevil (Anthonomus grandis Boheman) larvae. The weight of female pupae was not significantly affected after 10 successive generations reared on artificial diet. Fecundity of in vitro F₂ females was significantly higher than that of in vitro F₁ females. Fecundity of C. grandis was not significantly reduced after 5 generations of in vitro-rearing. However, the in vitroF showed a significantly lower fecundity than all other in vitro generations. Females reared on boll weevil larvae had a higher pupal weight and fecundity than females reared in vitro, but in vitro-reared females showed a significantly higher survival during the most actively reproductive ages.