First, I think you will need to identify what type of ant you have? Any exterminating company will usually do this for free on a walk-in basis.
You need to know what they eat. There's a recipe on this site in the newsletter archives for Roach Balls. If the ants are the kind that like fat … or the kind that like sweet, they should take this in the same manner as roaches.
NATURAL ROACH REMEDY
We have used these roach balls for many years to avoid having to have exterminators spraying toxic chemicals in our house. The recipe was shared with me from another person who had used it successfully for many years and had shared it with others who had great results. It works!
8 oz. Boric Acid [we find ours at a drugstore]
1/2 c. white flour
2 T. white sugar
1/2 small onion, minced
1/4 c. shortening
Cream shortening and sugar. Mix onion, boric acid, and flour. Add to sugar mixture. Blend well. Add enough water to form a soft dough.
Form into balls and place in small cups or lids. If you use cups, place them on the floor on their side for the roaches to crawl in. Lids are convenient to push under things, so you can flatten out a ball for areas like stove, refrigerators, etc.
You can also submit a question at this website. Maybe they take photos also if you can get a photo of the type of ant you have? There are a lot of natural solutions/methods on this site: http://www.asktheexterminator.com