Eww! As one who hates crawling things, especially in my house!, I empathize. I'm not an ant expert, and the suggestions below sound good. I didn't see anyone mention cinnamon. I don't know if it kills them, but it did keep them out of our ground floor condo after we found them sneaking in. We sprinkled the cinnamon liberally on the slider door frame and the patio and they actually stopped! I don't know what kind of ants they were, so I don't know if this will work with all types.
Shortly after we moved into our house, and older home, we discovered rats in the garage (thank God not inside!!!) and big black ants inside. There weren't a ton of ants, but I couldn't figure out where they were coming from, therefore how to stop them. We called a pest control company and both the furry and six-legged "guests" were gone in no time. Though not the least expensive solution, it was quick and guaranteed by the company or they would treat again. There are a few good companies that use kid/pet/earth friendly treatments. Good luck!!