A friend sprinkled that stuff on an anthill. he used the ortho brand, probably the same thing, yes it smells like straight up ass. Followed directions, and one of his girls, seen the dead ants in the hill we guess, and feasted, you could see where she dug a bit, and died two days later. He said he could tell she was poisoned a few hours after she got caught on the mound, but there was nothing he could do.
I use the ortho in the front yard, it works wonders on the little sob's, but in the back yard where the girls can get to it, I cover the area I sprinkled with a burlap sack and put a cinder block on top of that to keep them absolutely OUT of it, after seeing what happened to Mikes chicken.
Make several steps to ensure they can NOT get into it, dig in it,eat anything around it etc etc.
Also, just a heads up. The nature of fire ants, their mounds can be HUGE, you may only see a bit on top but it can have 40k bastards down in it and another 40k eggs spreading a few feet !! So if you think you can just tappy tap a tinkle sprinkle from a tiny baby teaspoon on them,... think again.
Typically when you poison them, you'll kill about 80 percent, they will split up and tend to form smaller mounds 5 to 10 feet out from the original one, so you may need to watch very carefully for this, and hit it again, sometimes 3 to 4 times to finally be rid of that mound entirely,.
Also, some info that may nor may not be useful. Their bites last year were very potent, this year they don't seem too bad (or maybe me having bees now and being stung some times made me a bit immune to it, dunno) .. either way it is NOT a joke, while you may survive the blister, pus pimples etc, if that is on a foot etc it CAN infect, and you get a staph set in there, NOW you have a problem.
Aaron