Use baits in their paths, the thing is, you need to find the right baits. Identifying the ants goes a long way to figuring out what baits will work. I have never liked Terro, never works for me. I prefer combat gel, a few dabs in their paths is all it takes. Takes a while before they discover it, but soon you'll see them all around it, leave them alone. They take it back to the nest and it kills from there. In about three days, they will all be gone.