Ants live in colonies, or ant nests. Ant nests are often referred to as ant hills because they are marked by mounds of dirt that look like little hills. Finding an ant nest is important because it is where the queen lives. When you destroy the queen you will destroy the colony because there's no queen to mate and produce new ants.
Mix 1 cup of borax with one cup of sugar on a paper plate. The sugar will attract the ants in the nest, but the borax will kill them.
Fold your paper plate in half and sprinkle the borax/sugar mixture all around the ant nest. The ants will come out and take the deadly mixture back down into the nest.
Wait 48 hours for the borax/sugar mixture to kill most of the ants. Then boil a gallon of water and pour it over the ant nest. This will kill any remaining ants as well as cause some of the nest to cave in.
Level out the now empty ant nest with a shovel. This destroys the opening so that no new colonies can settle in the nest in the future.
Use a permethrin spray if the home remedies are not working for you. The University of Michigan recommends this liquid for killing ants in their nests. Soak the nest with the spray. You will need 1/2 gallon of permethrin spray to treat a large ant nest.