As you know, keeping fire ants away is an ongoing process, but this stuff has really helped. No more "migrating" mounds. Also, I put a bag of insecticide out with my spreader every other month or so. I've heard that using different type chemical each application is best.
That fine powder is pretty nasty stuff. I got a lungful when a sudden breeze blew a cloud of it into my face a couple of years ago. I couldn't stop coughing for about 24 hours afterward.