SummaryWhey and yeast products were fed to small caged colonies of newly emerged honeybees to determine their effectiveness as pollen substitutes. Bees were able to rear brood to the sealed stage when fed all diets with the exception of whey alone. Brood rearing was greatest on pollen, Wheast or 2: 1 yeast-whey formulations. All yeast-whey formulations, however, were inferior to pollen and Wheast.