Ants

We have ants in various places around the house and it's driving me nuts! I can't figure out where they're coming from or what they're after. They travel along the baseboards, so I sprayed those with some stuff (with no kids around, then wiped down). Seemed to help the problem there. This is in the living room! My thought is they're coming from the front door, but I don't know how. And there's no food or anything to tempt them -- I even cleaned the hardwood floors yesterday! They were also in Carter's room, coming in under the baseboards (which is also the front of the house). After spraying last week I haven't seen them again. Anyone have thoughts as to why they're here and how to stop them?