Dry Ice is heavier than air so it will find its way to the bottom of gopher dwellings. Place 1 to 2 inch pieces as deep into each hole as can be reached and fill the front of the hole with dirt. If you miss some holes the process may have to be repeated. Jerry Yamamoto of Hayward, California reports that he successfully used Dry Ice to eradicate regular Argentine ants from his front yard. Perhaps this could work on fire ants too.
provide dry ice products such as: Pellets, Rice Pellets (Dry Ice Blasting),
Micro Pellets, 1/4 inch , Special Cut Blocks, Slices, Nuggets and High Density