Colony reproduction in which one or more queens and a number of workers separate to establish a new colony.

When the queen, or queens, are accompanied by a small number of workers and they leave the main parental nest, the process is called budding.

When major portions of the colony separate, each with one or more queens (as in army ants), the process is called fission.

Swarming also applies to the mass exodus from the nests of reproductive forms at the beginning of the nuptial flight.