When we lived in GA, our next door neighbor (80 yr old farmer) told us to use grits (uncooked) right before it was supposed to rain. (I'm sure rice could work this way also, esp. if it's instant rice) anyways.. the ants take the grits and eat them, and feed them to their queen, then it rains and they must drink it? and the grains swell and the ants (queen in particular) explode.
HTH!