Adults of Melanoplus bilituratus (Walker) were reared in the laboratory as groups of pairs, as groups in association with mature and immature males, as single pairs, and as groups of unmated females. Females of grouped pairs produced a larger number of eggs per pod and laid a greater total number of eggs that were more viable and hatched at least one day earlier than those of other groupings. Hatchlings of grouped pairs were more robust, 29% reaching the adult stage, whereas only 12% of nymphs from eggs of single pairs reached adulthood. Eleven per cent of the eggs of unmated females were viable, although only one hatchling lived to become an adult. Females of grouped pairs, of single pairs, and of those that were unmated reached their peak egg production in four, five and seven weeks respectively, after becoming adult. Young females matured three days earlier when mated with old males than when mated with males of their own age.