I spray carburetor cleaner on the mounds. Attacks the exoskeleton.
Another option. I use this in the home also.
Hi Shelia. Pour equal parts of water and white vinegar into a spray bottle. Use this to spray on anthills and everywhere you see the ants. Ants hate the smell and taste of vinegar.
For permanent results "feed" them with ant bait that they take back to their colony. It takes about a week, but it kills most of the horde. Repeat when the bait is gone. Personally I like the gel ant killer because I can apply it to surfaces that don't get rained on like the bottom of elevated flower pots or tree trunks. Also applying it under something helps prevent pets from licking it.
Hi Sheila: This is what I used for my ant problem, it may work for you, too.
Make a mix of 1/2 baking soda and 1/2 powdered sugar. Mix well and put around the spots they are in your garden, or inside your home, it's harmless to people and pets. For outside use, you can put it in a bottle, like a pill bottle or something like that. Cut a hole on the edge of the cap, and lay the bottle on it's side so the ants can come in and get the mix. This way, it stays dry if it should rain. They will take it back to the nest and it should kill them. I'd keep it out there all season if you can. The mix makes a gas and the ants can't pass gas, so it kills them. Anything else that eats it will just taste the baking soda and say "Yuck" and walk off. It won't hurt anything that can pass gas, so it's completely safe.
It helps to know what type of ant you are trying to get rid of, too. Try this site, scrolling down to see the different types of ants and how to deal with them. Good luck. https://www.thespruce.com/ant-control-4127879