The component of royal jelly that causes a bee to develop into a queen appears to be a single protein that has been called royalactin. Jelly which had been rendered inactive by prolonged storage had a fresh addition of each of the components subject to decay and was fed to bees; only jelly laced with royalactin caused the larvae to become queens. Royalactin also induces similar phenotypical change in the Drosophila melanogaster, marked by increased body size and ovary development [Wiki].