A new colony of the boll weevil ectoparasitoid Catolaccus grandis was introduced from Guasave, Sinaloa, Mexico to improve genetic variability of a 12 year old laboratory reared stock in Weslaco, Texas. The biological characteristics of the introduced colony were compared to those of the Weslaco colony. Developmental time was not significantly different among the 2 colonies, but the preovipositional period of the Sinaloan females was 3 times as long. The fecundity, net reproductive rate (Ro), and intrinsic rate of increase (rm) of females from Sinaloa were significantly lower than those of females from Weslaco. Generation time (G) and doubling time (DT) were significantly longer in the Sinaloan colony. These characteristics make the Sinaloa population disadvantageous for mass propagation and release to control boll weevil populations. Therefore it was recommended no to cross breed the introduced wild colony with the existing C. grandis stock.