Common Black Ants are usually a nuisance in the early summer months when they start to come into buildings in search of a food supply for the Queen and her young, forming long trails and infesting areas where food is stored or left.
Also during the mating season (commonly referred to as flying ant day) when winged males and virgin Queens emerge in substantial numbers.
After a new Queen has overwintered she will emerge to begin the task of starting a new colony.
Colonies are controlled by a single Queen with large numbers of workers carrying out duties each assigned a single task to be carried out throughout their lifespan.
Other Ant species that infest buildings are Ghost Ants and Pharoah Ants. Much smaller in size with multiple Queens and "satellite" colonies quickly infesting the fabric of buildings.
Different control methods are required for these types of Ants as sprays and other methods can in fact worsen the infestation, causing the colonies to split and spread further throughout the building.