I'll second NYMM. Sounds funny, but it works great without having to put out poison.

We have a little garden area in the back yard. I was weeding one day and saw a few large ants around a flag stone. I tipped the stone over and holy shit, a billion of those things went ape shit. I could see they had quite a few tunnels all about.

Went into the house, filled up the spaghetti pot, brought it to a nice boil and poured it on the hole.

No more ants.