I live in Los Angeles and I use to live in Alpine. Southern California is a giant ant hill. I think this year has been worse because there is so little rain. Every summer I’ve had to move my Sugar into the frig. and set the cat’s food in moat of water and oil to keep the ants from swarming. This year I also sprinkled clove powder around the baseboards and that seemed to work really well.
I do a lot of landscaping and I try to discourage my clients from using poisons because they do nothing to decrease the ant population in the long run and the poison leaches into our water. Ants damage plants by catering to aphids, scales, and sooty mold. They can be controlled with insecticidal soaps ( like JungleRain or by mixing 2TBS of Dr. Bronner’s 1/2TBS vegetable oil and several drops of orange oil into a quart of water and spraying your plants) and also growing season oil spray is very effective.