Boric acid kills ants, but the high percentage to the bait mix usually kills them immediately. What you want is a lower dose — they take the poisoned bait back to the nest to share with the queen and the others. Commercial baits contain about 10% boric acid, you want about 3%. It seems that kitchen-type ants like either sweets or grease. Get some of the commercial bait and mix it with sugar water or grease (shortening, meat drippings, etc), 1/3 bait, 2/3 sugar water or grease. Boric acid is mildly toxic (mostly as an irritant), so I put the poisoned bait in a small screw-top jar with some holes put in the top, saved for just this purpose, and put the bait in that. It keeps it away from curious cats, and the dog can’t get into it even if they knock it onto the floor. LABEL THE JAR!