I don't like fire ants. They have a purpose, but not in my yard. They build mounds, and give me a target.
There are two basic types of insecticides for fire ants. One type is placed on the mound, some require watering after application, and the mound is supposed to die within a short period of time. I found it works, but only for a short period of time, unless rain is immanent. The poison is extremely toxic to the ants, and sometimes doesn't kill the queen. The ants will migrate, and a new mound will be formed.
The other is a bait. Instead of placing it on the mound, it's scattered around the mound, and best if the mound is not disturbed. The ants will forage in the morning, and evening, bring the bait into the mound, and eventually all are killed; including the queen. This one I like, since the final result is complete eradication of the colony. It takes day, but the ants are eventually terminated.
At the start of this season, I had around a dozen fairly large mounds in the yard. With a little effort, I only will find an occasional small mound. Usually this happens after a rain event, and I think the ants are from somewhere else. Large mounds can have swarms of ants leaving, and they can fly a substantial distance.
For those that don't know fire ants, they have a stinger like a wasp, which they use to kill anything they perceive as an attacker. Stand on a mound, and within seconds, hundreds of stinging ants will swarm up your leg, and start stinging. The stings leave painful pustules that can become infected. That, and some are allergic to the venom, which can lead to anaphylactic shock. Enough of the venom, and even the strongest can succumb. We had a local motel find a guest swarming with ants, and the report said they are what killed the man.
After years of watching fire ants, I realized our highway system was instrumental in their spread. The highway is full of dead insects, trash with food, and road kill. The mowed edges, abundance of food, and unimpeded spread are a perfect environment for the ants. Over time, they've now reached any parts of the U.S. where the ground doesn't freeze to a depth that kills the ants.