The oviposition behaviour of the cowpea weevils, Callosobruchus rhodesianus (Pic.) and Callosobruchus maculatus (F.) on clean and egg-laden adzuki beans was examined in choice and no-choice experiments. The oviposition rate of C. maculatus was greater than C. rhodesianus in both experiments. Both weevil species were able to distinguish between clean and egg-laden beans. Discrimination by both species was greater against seeds with 12 eggs than with 6, regardless of which species had previously laid eggs. There was a weak indication that the presence of C. maculatus eggs at high densities might reduce the oviposition rate of C. rhodesianus.
