I'm having an issue with ants myself. I think one cause is with the wet weather, the ants are looking for someplace dry, and the house qualifies. I also suspect that with it being winter (only now moving into spring), there just wasn't as much food outside - I know they will farm aphids in the summer, and there tends to be some dropped fruit or other things for them to munch on that does not exist now.

I've been using advion ant gel (which is a chemical pesticide), but I'll put a glob in the crack between the cabinet and the wall or other spots where the ants can get it, but other things can't. It is generally effective, but this year seems worse than usual - I'll kill one infestation, and then a week later, another one will start.