A friend who lives in Georgia said when he was a kid they almost had the Fire ants killed off from planes "crop dusting" large areas of land but the environmental regulations made them cease treatment and the ants came right back over time.
I got to play with some mounds when I used to visit there and they are like no other ants you'll ever encounter, They are very aggressive. Hunters will often place the deer antlers in a mound and in a week or so they are clean and spotless! Its scary!
I really feel for you guys who have to fight these all the time, in most places you cant go more than 5 feet any direction without seeing a mound.