In colonies of social insects, any group of individuals which are structurally and/or behaviorally distinct and perform specialized tasks; for example, the "soldiers" of termites and ants and the workers of hornets and honeybees.

1. Queens, which are typically the largest ants in a colony: After selecting a nest site, a queen will begin laying eggs and caring for her brood. The first workers in the ant caste that develop assume brood care, leaving the queen to simply lay eggs.

Ant colonies can have single or multiple queens. The number of queens in multiple queen colonies varies by species, ranging from a few queens to nearly half the population in a colony.

Depending on the ant species, queens may live from months to years.

2. Males, that serve one purpose which is to mate or breed with the queen: In the ant caste, males typically die soon after mating or are forced to leave the colony and are normally alive solely during the colony's reproductive stage or period.

3. Workers, which are sterile, wingless females form the main members of the colony: In the ant caste, the workers perform the tasks necessary for the survival and growth of the colony; such as, foraging for or finding food, caring for the brood (eggs, larvae, plus the queen), and excavating or enlarging the nest.

1. A rigid system of class distinction.
2. A form of stratification defined by unequal access to economic resources and prestige, which is acquired at birth and does not permit individuals to alter their rank.