This answer was given by another Hometalk Helper and I copied it down.
2 cups vinegar, 2 cups water, 3 tablespoons of Blue Dawn dish soap, 3 tablespoons of salt. Mix it all together and put in a spray bottle. Shake the bottle before each use. Spray the ants and their trail. As you can see, it's non-toxic. Yay!
Mix equal amounts of borax and sugar. Dampen cotton balls in water then dip in borax/sugar mixture. Place cotton balls on a piece of waxed paper (or plastic wrap) where you see ants. They will be attracted to the sugar and some will carry the borax back to the nest. Others will die near the trail. Also you can spray 409 Cleaner around doors and windows - they will not cross over it (the exterminator told me about this trick). I would suggest you test on a small area to make sure it doesn't harm your your paint.
I use peppermint essential oil
We have used a product called Terro, you can get it at diy stores in the pest control section, just follow the on the package directions. It is a liquid that draws them, they feed on it and in a couple of days they will have taken it back to the colony and no more ants.
Here's a simple DIY recipe to deal with ants inside