Vinegar does not kill ants. Vinegar can deter ants from entering a home or building by overpowering the scent that ants use to follow in another ant's footsteps.
A mixture of equal parts water and vinegar prevents ants from nesting indoors and foraging for food. Fill a spray bottle with the vinegar solution and squirt areas that are likely to attract ants like pet food bowls and other food sources. While effective against ants on hunt for food, this solution does not stop ants that are already nesting in a home. If ants are well established, place ant bait in problem areas to attract the insects and wipe out colonies.