Straw itch mites
Some studies have shown moderate benefits from releasing these beneficial mites, but other studies have found none. However, the most dramatic effect has been the large rashes that researchers have gotten from some of the stray mites that they were releasing. Ooh, itchy, itchy, ITCHY!
Two wooden blocks
As in "place ant on middle of Block A and then rapidly apply Block B." Very effective on an ant by ant basis, but a lot of work for a colony with a quarter million workers!
DO NOT USE IT! It is expensive and dangerous to the environment and to your health to pour gasoline onto the mounds. Extensive or frequent use can threaten the purity of your ground water. Igniting the gasoline intentionally or accidentally does nothing to improve its effectiveness, but it can pose a serious threat to your health and property.
Household cleaning products
Most don't work at all. Some act as a repellent, causing the colony to build new mound a few feet away. Anything that does work is likely to be expensive and bad for you, your yard, and the environment.
Exhaust fumes from a car or riding lawn mower can be pumped into fire ant mounds. About 12 years ago, I tried it with my old VW Superbeetle. After about 15 minutes the result was that most of the ants were motionless, but 30 minutes later, they woke up and went back to work. Maybe 30 to 40 minutes of exhaust fumes would be effective, but that is a long time and I hear that plugging up the exhaust systems of gasoline engines can be pretty hard on them. (Fortunately, my VW still worked, but so did the ants.)
Mechanical devices that cut, chop, stir, mix, pound, or grind up fire ants in their mound can be effective during times of the year when most of the colony is up in their mound. The benefit of these devices is that they leave no chemical residue. The problem with them is that they are usually expensive to purchase, labor intensive to use, and inefficient in dealing with colonies under rocks, roads, sidewalks, or shrubbery.
These can be effective, but like hot water they will kill grass and shrubbery. Also see comments about mechanical devices.
I don't know of any that work. With the one I tested, fire ants moved in and built a mound around it after about a month when the weather turned cold and the vibrating rod was nice and warm.
Electric bug zapper grids
These dramatically kill ants that run across them—the problem is that all fire ants are not like lemmings. A large majority of the colony runs the other way while only a few stay and "fight" the zapper.
Might work, but I would be awfully nervous around a microwave oven big enough to rapidly heat the ground up to 3 to 4 feet deep!
Contrary to what their name implies, giant ant eaters in South America do not eat ants. They eat termites. Besides who would want a 200 pound animal with claws and arms as strong as a bear wandering through their neighborhood! Our little native ant eater, the armadillo can be enough of a problem.
Modest Proposals for Eradication
As in "Pay me $1 per queen and 1 cent per ant and I will solve your fire ant problem." Nice proposal, but with up to a quarter million ants per mound and mound densities of well over 100 mounds per acre, this could easily cost $25,000 per acre per year—a pretty good business deal if you can get it!
Additional information about fire ant control and lots of other good fire ant facts can be found at the following websites: