Female honeybee larvae have two possible fates. Larvae raised as potential queens are nourished with royal jelly, a dish containing the protein royalactin. Female larvae destined to become worker bees receive royal jelly for just three days: Then their diet switches to honey and beebread, a fermented pollen product produced by bees. A team of researchers led by May R. Berenbaum of the University of Illinois, Urbana-Champaign, wondered how these differences in diet lead queen bees to be fertile but leave worker bees incapable of reproducing. The team wanted to determine whether worker infertility is due to a nutritional deprivation or whether something in the workers’ food chemically castrates the larvae. Their study supports the latter explanation. The team reports that p-coumaric acid may act as a chemical castrator by altering the expression of genes required for ovary development (Sci. Adv. 2015, DOI: 10.1126/sciadv.1500795). The compound is common in pollen, a major constituent of the worker bee diet, but it is not found in queen bees’ royal jelly. When the scientists added p-coumaric acid to royal jelly, the would-be queen bees developed smaller ovaries.