Cucumber peelings or slices. Ants hate cucumbers and will do anything to not be any where near them. I discovered this solution in one of those Graham Haley Helpful Hints books and tried it when I had a recent ant infestation in my apartment. The ants were mounting an invasion of my bathroom. I went out and bought a couple of cucumbers, peeled them and put the peels in cheese cloth and hung it from the drain pipe under the sink. The ants were gone within hours.
Just looked up ants in his book and he has other suggestions too.
Sage or white pepper will repel ants if sprinkled around affected areas.
He also says to draw a chalk line on the floor or the wall where the ants march. Says ants won't cross a chalk line.
He also suggests leaving apple pieces, core or peelings where ants enter. When brought back to the anthill, the acid in the apple kills the queen and the colony.
If you like natural/generic remedies for all kinds of things, pick up his book. I've been trying quite a few of his suggestions with successful results. Haley's Hints: A Compilation
and Haley's Cleaning Hints