Ants have three castes, namely queens, males and workers. Queens and males are the reproductives. Workers are sterile wingless females. New ant colonies are started by a single fertilized queen that lays eggs and tends her brood (larvae and pupae) that develop into worker ants.
 

Tending of the brood is then taken over by the worker, which may shift the brood from place to place as moisture and temperature fluctuate in the nest. When workers forage for food for the queen and her young, they often may enter houses and become a nuisance by their presence and contaminate food.