What's the best method?

This looks like it would be fun to try

You talking about red harvester ants or fire ants?

I had a lot of them. I stir the nest. They come boiling out and I sprinkle Sevin dust on them. I assume that they carry it back down into the nest on their bodies. No more ants.

Amdro fire ant killer mound treatment works great on red harvester ants.
Just sprinkle the yellow granules around the mound and along their trails. They will be carrying it back down the hole before you get finished. Rarely it will take 2 applications but it works very well.
Also works great on fire ants.

I've had the best results using Amdro Ant Block granules.

Reliably kills a broader range of species ( 25 species vs the usual 1 - 6 species).

Orthene. It's on my list for the next outing. I use cheap wasp spray while mowing. Got that PSA from NewGulf.

I wish that we still had the big red ants around here. When they disappeared so did the horny toads.

I've got a few beds of the harvester ants that I leave alone. Fire ants, on the other hand, are a different story. They all need to die.

I thought the fire ants were to blame for that. But In places that don't have hardly any fire ants like out here in west Texas, the horny toads have almost all gone away.
We just kill the red ant beds when they are in places likely to sting someone. Man those stings hurt.
But we leave them alone when they are in low foot traffic areas to try and help the horny toads. Starting to finally see a very few horny toads around the last couple years and have some decent amounts of red ants around here now.

Navarro County, We have a ton of harvester ants. They love to mound up near the feeders. Never seen a horny toad on property.

Sevin dust works for me on harvester ants, just dust the trails as well as their hole.

Just picked up a jar at Lowe's. it was on the same display with wasp spray. Go one of each.

I remember reading an article back in the 80's that's stuck with me. It made a pretty good case for the decline of the red ant being at least partly to blame for the rise of the fire ant.

I don't remember the exact details. Something about our native red ants being our only natural enemy of the fire ant. When we started wiping out red ants in the 70's it opened the door for fire ants to move in and set up house in the 80's. When the red ants went away, so did the horned toads and quail, because the fire ants moved in.

I can honestly say I don't see NEARLY as many red ant mounds these days as I did back in '74. And the few I see are tiny in comparison. I can't even remember fire ants being an issue in '74.

89 Octane
I a pour about half a quart down The main hole in the mound and they're gone the next day or 2.

I leave harvester ants alone. They are pretty harmless out in the pasture. And usually when I see those, I DONT see fire ants. As stated earlier, all fire ants need to burn in hell.

Dawn dish soap...squirt it in the hole, kills leaf cutter ants for good, haven't tried it on fire ants because we don't have any.

I always heard they eat fire ants so I never messed with them

It doesn't seem to take much to run them off from around the house, not sure what I do. Water maybe. I leave them alone away from the house

red harvesters are a natural fire ant enemy, I leave them alone and have 2 large mounds on either end of the bldg. no fire ants within 75 yds. and the few I do find get amdro on them.