Insecticides kill only the ants who happen to make contact. Ant baits are more effective for ant control because they get carried back to the ant colonies where it is shared and can kill the colony. Once colonies are killed, then you can maintain the perimeter of the structure with a monthly residual insecticide spray, spraying foundation and soil along perimeter. For additional info from the Cooperative Ext. Agent:
http://lancaster.unl.edu/pest/resour...ntrol003.shtml