The best way to eliminate fire ants in your lawn and landscape is to use the Texas Two Step method. The first step is to use baits. These are slow acting and can require weeks or months to work but contain extremely low toxins. They are 80 to 90 percent effective. The worker ants take the bait into the hive to share with the queen, either killing or rendering her infertile. Put baits out when ants are actively foraging. Fall is an excellent time to bait as the ants will feed during the winter while you are indoors. Follow package directions carefully for best results.
The second step is individual mound treatment. These are fast acting to eliminate existing mounds. There are commercially available dust, granular and drench products on the market. Closely follow instructions on the label. You can also pour 2 to 3 gallons of boiling water on the mounds. This will be about 60% effective. The hot water will kill any grass or plants that are touched by it.