I actually found that plain old 20 Mule Team Borax does a great job with ants. Mix it with a little sugar or grain and scatter it where you you see their trails and they'll track it home. Even worked outside. (One day I saw a big trail marching from under a bush across the driveway, so I sprinkled maybe a tablespoon of borax across it leading up to the entrance of their hill. If I didn't kill them all they at least stopped coming out that way...)