We believe the house lizards (see below) eat these tiny ants. If so, they're going to become very fat lizards, because there seems to be an endless supply of ants.
Drop a little drip of condensed milk on the kitchen counter during the coffee-making routine, and ants will appear out of nowhere. Drop some tuna salad and they'll really have a party. Sometimes we come out of our little home office to find an episode of Wild Kingdom in the living room -- a tribe of ants carrying a dead moth or something across the floor.