Terro is one brand. We sell it in our store. It works very well and yes it will freak you out with the number of ants that show up, but eventually they go on to that big ant farm in the sky!

they sell a few different brands of a liquid bait that has boric acid and a sweetner. we just squirt a dab near the ants preferrably near their entrance and watch then feed. It can be a little scary at first as they gather but they do die. We usually are making follow up applications but have succes