Kill red ants naturally

Use Food grade Diatomaceous Earth. Sprinkle heavily around the ant hill. The ants will walk through it into their nest and kill the queen. If you want to get rid of them them inside, you need to keep everything very clean and dry as they are looking for food and water.

Borax or diatamacious earth food grade

We had several ant species building mounds under the brick decking causing it to warp and the bricks were uneven. We feed birds off the deck and I didn't want to use any pesticides. Out of sheer desperation and not wanting to spend a lot of money, I boiled water and slowly poured it over all the bricks above the mound. It took a number of trips, but they never came back. I'm sure they moved elsewhere unless it got to the queen ant. It was easy and cheap.....not sure how it would work in a garden or on grass. Try a test patch to see how the surrounding grass fares.

Cornmeal.....When You Find Them Sprinkle Around Hill The Red Ants WILL Carry The Morsels Back In The Hill, Where They Eat The Cornmeal, Well Cornmeal Expands AND So Do They!! Works With Regular Ants..

Cornmeal definitely works for inside. Boiling hot water will work also, but don't let it get on your grass. It will kill it. I've been pouring all the hot water from cooking rice in the winter in one certain spot and this spring that spot is still free of any kind of green life.