Workers from different nests begin to cooperate, and queens wander among nest sites. Supercolonies of Argentine ants, big-headed ants, red imported fire ants and little fire ants usually eradicate all other species of ants in the area. Pharaoh ants also form supercolonies, but are less aggressive toward other species. Control of supercolonies is a challenge. Only a small percentage of workers are out foraging at any one time, so killing foragers with insecticide sprays is ineffective.
Baits can work, but only as large quantities over long periods of time.
What's worse, as the colony is stressed, ant-feeding behavior may change, and baits become ineffective. Because the supercolonies contain tremendous numbers of ant workers, brood and queens, even if you kill large numbers of ants, replacements soon move in from unaffected areas. Pharaoh ant supercolonies in and around a building require that you bait, evaluate and rebait each infested site for six months to a year. You may also need to bait outside or apply a perimeter treatment. Permanent solutions are difficult, but possible.