Joe,
We, too, have had a very tough year with fire ants. We are in a severe drought, and they seem to be thriving in the dry conditions. Just yesterday, I spent the early morning digging for a new pond. I placed several dozen earthworms in a plastic shoebox for this year's hatchlings. I went to work for the morning, then decided to bring them in at my lunch break. Fire ants had invaded the shoebox, and were making their lunch of the earthworms. They made shorter work of the worms than the turtles do.
It is strange, I've actually found fire ants crawling on the adults. It makes me very nervous, but they don't seem to bother them at all. Perhaps their skin is just too impervious to the ants' mandibles?
I'm usually very conservative when it comes to chemical insecticides. The seriousness of these fire ants, combined with the fact that they thrive alongside humans and their pets, leaves me little choice. Based upon yesterday's carnage, I'm going to have to ask my neighbors if they mind me treating their yards. I'm going to look into that boric acid. I usually spray ant killer on the mounds and cover them with a shoebox and rock for about a week. Let us know how your treatments fare.
Take care.