For me a fire ant bite is worse than an average bee sting. I hate those things and have tried everything from gasoline to liquid nitrogen to cheap treatments from Lowe’s.
Unless you get the queen ... she’s deep down in the mound ... you aren't going to kill the colony. The best thing I’ve found is Advion Fire Ant treatment. It comes in a 2lb jug and I can treat 25-30 mounds with one jug. When I see one starting I just sprinkle about 1oz around the edge of the mound and leave it alone. Usually by day 3 they’re gone ... just don’t do it when it’s going to rain.
Oh yeah ... I get it for about $40 a jug of Amazon delivered to my door ...
No surprise on the sting being worse than an average bee...fire ants are related to wasps and bees, both. And yes, they bite...but it's only to anchor themselves so they can repeatedly sting the sh*t out of you with their abdominal stinger. If you didn't immediately brush a fire ant off, he'd keep stinging as he walked his *ss around in a circle, centered on where his bite anchors him.
The key to effective fire ant control is NOT just spot treating their mounds. Do this and likely you'll shortly see another mound pop up near by. Spot treat the mounds AND treat your entire lawn, too.
In Goose Creek, SC, where I had shore duty several years ago, we had fire ants in the yard. I got with the neighbors on either side and told them I was treating my entire lawn for them, and I recommended they do so as well ('cause guess where they'd go?).
We all went to Lowes at the same time and treated our lawns the same weekend. No problems the rest of the summer.
Back in the 80s, Diazinon was widely available, and it put the hurst on fire ants. Today, a really effective agent is cypermethrin, similar to permethrin, which acts as a nerve agent to these critters.