Although black ants can eat many types of food, they are particularly attracted to sweet substances. One successful foraging worker is able to communicate the information to her co-workers, with the inevitable result of vast numbers of worker ants invading and, incidentally, contaminating, suitable human foods.

Ants will nest in a whole variety of suitable sites, and mostly these are of no significance to man. However, sandy soil in general, and the sand used to form the base of paved garden paths, and in the foundations of houses, attracts local ants and nests may well be formed in these areas. Again, little trouble is caused unless the foraging worker ants invade buildings. This is highly likely if the nest has been constructed beneath the floor of the house and ants are adept at finding even the smallest settlement and other cracks in the structure; other ants are then "'led" into the building.

Flying ants

Sometime in the late summer winged and sexually mature males and large females will be produced and will emerge in large numbers over a short time period. This "swarming" will often occur from many nests at the same time and frequently in the afternoons. The winged ants fly away, mating on the wing, and eventually settling exhausted. The males usually die quickly and only a small proportion of the mated females will survive to found new colonies. Normally only one female will found each colony, but sometimes new colonies are formed in close proximity. If they do join up, then one of the females will assume dominance and kill the others.