Development and reproductive success of the solitary egg parasitoid Uscana lariophaga Steffan were examined after development in eggs of the bruchid storage pest Callosobruchus maculatus Fabricius reared at either low or high densities on cowpea seeds and laid at day 1 and 4 of maternal life. Both bruchid larval competition and maternal age negatively affected egg size, but the latter more than the former. Uscana lariophaga reared in small hosts developed slower, were smaller and produced fewer eggs compared to parasitoids reared in large hosts. Fecundity of the parasitoid was heavily influenced by host egg size. This was reflected in the values for the intrinsic rate of increase of U. lariophaga, which differed for wasps that developed in host eggs laid by bruchid females of different age. Wasps allocated marginally more female offspring to larger hosts.