I spent christmas with my family in Australia and they were experiencing a plague of ants, and in Australia the ants bite just to add to the problem further. I'd remembered seeing posts on Pinterest so we tried a recipe that is a mixture of borax and water and sugar and you dip a cotton bud in it and then put it in the line of ants. It worked every time! Was very impressed! This recipe as I said, isn't mine but I'll share it with you since it truly does work.
A Note on Borax - while it is naturally derived and considered non toxic and safe around pets and children, I would still keep it high above so children can't get into it and keep them away from the cotton balls.