Overall strategy Eliminate conditions such as moist wood and old stumps that provide good nesting sites. Search for nests and remove or treat them. Use baits to manage satellite colonies. Spraying foraging ants will not solve the problem.

Prevention Caulk cracks and crevices around the exterior of the home that provide entry. Trim branches and limbs of trees and shrubs that touch the building to keep ants from gaining access via these routes. Eliminate damp conditions that promote wood decay such as water leaks and poor drainage problems around foundations. Replace decayed or damaged wood and correct problems that caused the decay, such as clogged rain gutters or leaky roofs. Increase ventilation to damp areas beneath buildings and in attics. Store firewood up off the ground and several feet away from buildings to discourage carpenter ant colonies. Locate nests Observe ant activity at night. Follow trails. Sawdust accumulations with pieces of dead ants are good indicators. Main nests are often outside in old tree stumps, fence posts, or firewood piles. Satellite colonies may nest indoors on moist wood. Nest treatments Use baits to manage satellite colonies that you cannot find. Remove and destroy stumps and old wood with colonies in them to the extent possible. Where nests cannot be removed, treat with a desiccant dust (silica gel or diatomaceous earth) labeled for this purpose. Use a bulb applicator and insert the tube snugly into nest openings. Desiccant dusts have the advantage of being low in toxicity and are effective as long as they do not get wet. Fix leaky pipes and roofs to be sure no moisture can reach treated nest sites. Nests can also be treated with insecticides including permethrin, cyfluthrin, boric acid, or disodium octaborate tetrahydrate. Use a dust formulation labeled for this purpose. Apply dusts through colony openings and drilled holes. For extensive infestations, consider hiring a professional.