Which caste contains individuals that leave to swarm and form new colonies?

The caste that contains individuals that leave to swarm and form new colonies is the primary reproductives. In many social insect species, such as termites and some ants, the primary reproductives are the kings and queens. These individuals have the specific role of mating and establishing new colonies. During swarming events, they take flight to disperse and find suitable locations to establish new colonies, where they will begin the reproductive cycle anew.

The primary reproductives are essential for the continuation of the species, as they are responsible for producing the next generation of individuals. Unlike workers, who perform various tasks such as foraging and caring for the young, or soldiers, whose primary function is to defend the colony, primary reproductives are focused on reproduction and colony expansion. Supplemental reproductives, although they may play a role in reproduction as well, usually do not swarm in the manner that primary reproductives do. This specific behavior of swarming and forming new colonies is distinctive to the primary reproductives in the structure of their social organization.