Ant colonies are often found in cracks and crevices. For large colonies, typical baits simply will not do the job. The ant colony must be located and an insecticide must be applied directly. Commercially available baits often take too long with unnsuccessful results.
In order to destroy the colony, the queen must be target and eliminated. Simply killing the worker ants is not enough. A licensed professional looks to eradicate the entire colony one time.