Lupinus, when I see ants out in force in the veggie plants, I use Diatomaceous Earth on the ant trails.
I *could* use DE in the compost bin as well, but it affects the compost worms (it cuts their little bodies and they die) negatively. Ants dying I don't mind, but the worms work for me and I provide them a "home." Killing them on purpose just doesn't seem right.
So I use cinnamon in the compost and boiling water on anthills in the ground, Diatomaceous Earth on ant trails and ants on my raised beds and near my veggie plants. I haven't used cinnamon in the raised beds b/c the DE does such a good job. It's a one-stroke attack, and the enemy is vanquished.
Just to be complete, when I see ants in the kitchen (which I probably will this weekend due to heavy rains--ants seek higher, dryer ground), I spray the ant trails and the individual ants with Fantastik, the kitchen spray. Non-toxic and it takes care of 'em. I do the initial clean-up, and then I spray Fantastik wherever I can find an entry point. It usually knocks 'em down within a day.
I do NOT like ants in my kitchen....
I think this is my complete "ant attack" program:
-- cinnamon in the compost, maybe DE if worms are not present
-- boiling water and/or DE in the ground
-- DE in the raised beds near veggie plants
-- Fantastik in the kitchen, bathroom, anywhere they invade the house
I hope it works with fire ants. People who haven't experienced fire ants just think they're like regular little Argentine or sugar ants. No. They're bigger, meaner, they bite, and many people are highly allergic to their venom, formic acid.
Ants are of the family Formicidae. Formic acid is what the fire ants inject into your body when they bite you. Yeah, it burns, whence "fire." Nasty little boogers.
Good luck, Lupinus.