We don’t have fire ants in N California.
We have yellow jackets that tunnel in the dirt, make their hives/nests, lay eggs and hatch more yellow jackets.
When we moved to our home decades ago in the drought, we had several colonies of yellow jackets under the barely alive ivy. We could not use our front door. Sprays did basically nothing.
Our local ACE guy recommended a stick that you started it to smoke and stick the stick into the tunnel and but a brick over it and let the smoke and fumes kill the wasps or gophers.
He told me do it at night and fortunately warned me to have a hose connected to the nearest faucet with a good nozzle incase the ivy caught on fire.
My oldest son and I each put in a couple of the lighted sticks for a total of 4 sticks into their vent holes and put a brick over each hole to force the smoke down and to circulate poisonous fumes.
Our youngest son was standing on the steps going up to our front porch with the hose and ready.
After my oldest son and I started the sticks burning and put a brick on the exit hole, we walked away to get away from the fumes and smoke.
As we were walking away, we heard our youngest son say the S word and start using the hose.
The dry ivy was burning up to a 3’ radius from each lighted stick.
The little guy did a good job and keep the 4 fires under conrol. We couldn’t get up to where he was due to the smoke, fire and noxious fumes.
After about 5 minutes, a fire truck came up and put out the fires. A neighbor had called 911 and reported the fire.
The firemen laughed and knew what had happened. They hosed down the area and put out the fires. One of them lived a few blocks away and came back the next morning.
He brought a can of cat food and a liquid wasp killer, we could buy at Ace.
He opened the can of cat food and put the liquid wasp killer on top and set the can between the 4 hives.
In about 15-20 minutes, there was no cat food left in the tin. The surviving wasps had taken it into their nests.
He told us to use another door to get in and out of our home for about 2 days and the wasps would be dead.
After about 2 day we didn’t see any live wasps. They had been dragging the dead ones out of their hives and leaving them on the ground. These were eaten by other wasps from other nests. That ended up killing those nests.
For two decades, I used that method to get rid of the wasps, and then the green eco freaks banned the wasp poison.
A few people in California die each year from massive yellow jacket wasp bites.
One of our friends was able to buy the poison in Oregon and Nevada for a few years. Now no one can sell it.
Fortunately, the mosquito control people will spray the nests with something that kills the yellow jackets.
Wow. Hate those boogers! And they are sooooo aggressive!