If you know where the ant hill is then you can try this. Get one of those pots that has a holes in the bottom or ake holes in it, make sure it is big enough to cover the hill. Make a pot of boiling water. Place the pot upside down on the hill then pour the boiling water so it goes thru the holes. The boiling water will kill the ants. Supposedly the pot traps the ants so that the water can get them.
I have not tried this but heard it works.