In a solitary species of bee, males gain chances to mate with females when they help guard the little ones.

Teamwork makes parenting easier, even for some insects. Male and female Ceratina nigrolabiata bees pair up temporarily during the breeding season to care for offspring and defend nests.

In bees and other insects, any care that offspring receive generally comes from the mother. But when Michael Mikát at Charles University in Prague and his colleagues examined 460 C. nigrolabiata nests, nearly 90% held a male–female pair of bees. While female bees were foraging, males remained inside the nest to protect it from enemies such as ants. Males protected nests even when the offspring belonged to another male.

The researchers also found that C. nigrolabiata females usually mate with several males. But a male gains mating opportunities with a female by forming a temporary partnership with her. Indeed, the team observed that males gain more offspring the longer they guard a nest — an average of 0.638 offspring for every 7 days of guard duty.