For nests found in structural voids or inside wood timbers, a dust formulation can be applied in a very light thin layer and be very effective when needing to control ants. Dusts do become repellent when applied to heavy; using a compressed-air duster is very helpful in treating any areas. You can inject the Ant control dusts into wall voids either through existing openings around plumbing and electrical lines or by drilling into the wall or sheet rock and creating a access holes.