Since the ants are already in the house the best solution is to get some ant bait stations. The bait will draw them out of the walls and be more thorough in the overall kill than spraying them. I will take a little longer, but will be worth it. Do not spray them if you decide to use a bait. Remember, spraying will do a quick kill and set up a repellant while bait is used to entice them. Bait and repellant counteract each other.