Killing only the ants you see will never get rid of the problem.
You need to kill the colony underground. Learned this over years of trying.
A simple solution that works, although I've not yet tried on it on fire ants.
Mix baking soda and confectionery sugar together 50/50, dry. Place near the active areas.
The sugar attracts the ants, they take the concoction to their nest, unable to separate the two ingredients, the baking soda reacts in their digestive system and kills them, in their home. All of them.
