A unique “choreography” between two ant species suggests a distinctive partnership in which one provides a carwash service to the other.
One June morning 20 years ago, Mark Moffett, an entomologist at the Smithsonian National Museum of Natural History, was drinking coffee behind a cottage in Portal, Ariz., when he noticed something odd in the mesquite desert.
On the ground, as Dr. Mof... [1525 chars]