We have a woods behind our t/h and were bothered with black ants as well as a number of other insects. We bought Dursban (it is granular)and sprinkled it around the foundation then sprayed it with water. Inside the house we used Tero. It is a thick liquid that you paint on a small piece of cardboard that you place where the ants travel. We also used the small ant traps that can be purchased in most stores. Great results within one week but we are being vigilant.