If it is not clear where the ants are entering, then treat a 2 - 4 foot wide area around the entire building. This control method is temporary and retreatments may be necessary. Common insecticides for treating the building exteriors are listed below. Read all label directions carefully before buying insecticides and again before applying them. Information on the label should be used as the final authority.
Outdoor nests can be very difficult to eliminate without chemicals.
Using water to flood nests is usually not effective. Use of gasoline also is ineffective and causes environmental pollution. Repeated drenchings of a nest with an insecticidal soap solution is sometimes effective in forcing an ant colony to relocate. There is no scientific evidence that spearmint gum, red pepper, orange peels, or various herbs repel ants effectively. Remember you must kill or relocate the queen to control an ant colony.