Juvenile hormone levels reflect social opportunities in the facultatively eusocial sweat bee Megalopta genalis (Hymenoptera: Halictidae)

► We measured juvenile hormone (JH) in a bee with flexible social behavior. ► We compared queens and workers as well as social and solitary reproductives. ► JH increased from eclosion to reproductive age in nesting, but not caged females. ► Workers had lower JH levels than queens, but not solitary reproductives. ► Results support a role for JH in the evolution of reproductive division of labor.