When workers of the thelytokous Cape honeybee, Apis mellifera capensis, come into contact with colonies of the neighboring arrhenotokous subspecies Apis mellifera scutellata, they can become lethal social parasites. We examined the inheritance of 3 traits (number of ovarioles, number of basitarsal hairs, and size of spermatheca) that are thought to be associated with reproductive potential in A. m. capensis workers. To do so, we produced hybrid A. m. scutellata/A. m. capensis queens and backcrossed them to either A. m. capensis or A. m. scutellata drones. We then measured the 3 traits in parental, hybrid, and backcross offspring. We show that the 3 traits are phenotypically correlated. We also show that the expression of ovariole number, basitarsal hairs, and size of spermatheca is influenced by the genotype of the individual and the rearing environment but that the influence of the rearing environment is less important to the number of ovarioles. We hypothesize a single recessive allele (l), present at high frequency in natural A. m. capensis populations, which when homozygous causes larvae to elicit more food. This increased feeding as larvae causes resulting adult workers to develop more queen-like morphology and increased reproductive potential. The number of ovarioles, in contrast, appears to be under independent genetic control.