Ant expert at your service!
I've tried every commercial ant killer on the market with no success - the little bastages just stuck their tongues out at me as they munched out on what was supposed to kill them. And I have cats so I don't want anything that they can get into.
So I got some small baby food jars, poked a few holes in the tops and filled them with cotton balls. Then I saturated the cotton with a mixture of 1 cup of warm water, 1/3 cup of sugar and 2 tsp of boric acid. The mix proportion is important because the idea is they come in and get little bits of the soaked cotton and take it back to their nest - bingo! Weapon of mass destruction. If the solution has too much boric acid, it kills them on the spot, which you don't want.
Set the jars around where the ants hang out. In a couple of days, they'll be a memory. You can get powedered boric acid at any hardware store in the bug killer section. The stuff I get is in a red bottle and it's called "Maxx" something - it doesn't say "boric acid" on thepackage but read the ingredients and that's what it is.