The cosmopolitan bee genus Ceratina, often referred to as small carpenter bees, is the sole lineage of the tribe Ceratinini, and closely related to the more familiar carpenter bees. They make nests in dead wood, stems, or pith, and while many are solitary, a number are subsocial, with mothers caring for their larvae, and in a few cases where multiple females are found in a single nest, daughters or sisters may form very small, weakly eusocial colonies (where one bee forages and the other remains in the nest and lays eggs). One species is unique for having both social and asocial populations, Ceratina australensis, which exhibits all of the pre-adaptations for successful group living. This species is socially polymorphic with both solitary and social nests collected in sympatry. Social colo