Permethrin is what I used on fire ant hills. Same as I use on mosquitos and roaches. On a cold morning, they will be up close to the top of the hill looking for warmth. Just poke a hole in the top and when they come boiling out spray them down good. They will die and when their buddies come to remove them, they die too. I have done a bunch this way and the hill dies.
Thats what I do! I use Home Defense by Ortho. Catch them on a cool sunny morning and they are all in the top of the hill with their little white larvae. Rake the mound open and spray. You will kill thousands and the mound dies and it"s kind of satisfying to come back by in a few minutes and see the carnage.
