I'm going to try this. Here in Florida there are lots of ants and if there's anything in a house that will attract them, they come in like you said, "not two by two, but thousands..." I've read all kinds of different natural ways to keep them away from the area directly around the house.

There are also "crazy ants," that look like sugar ants, but they are really something. I read that they are not indigenous to the USA, but are in Africa. And those ants even eat through wiring and electronics.

Here's a link with a little about them: Article Link