Oh, I do know how you feel.* I've had a massive invasion of sugar ants in my home and it's been an all out war!*
We need to id your ants so we know what to use.* DO NOT physically try and do something to any ant hills you find.* My hubby did that and the ants moved and set up more colonies.* Now it's a real mess.* I don't remember where you live, but do you know if these are fire ants?* Maybe this will help you to id them.
http://ohioline.osu.edu/hyg-fact/2000/2064.html
Newt
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.