In the deserts of southeastern Arizona, tiny cone ants have been found grooming much larger harvester ants, licking their bodies and even entering their open jaws. Entomologist Mark Moffett, a research associate at the Smithsonian's National Museum of Natural History, documented this first-of-its-kind ant interaction. The behavior, likened to cleaner fish in oceans, was reported this week in the journal Ecology and Evolution.
Mark Moffett spotted the unusual partnership one morning at a research station in Arizona's Chiricahua Mountains. While watching worker harvester ants (Pogonomyrmex barbatus) forage for seeds, he noticed some standing unusually still with mandibles open. Upon closer inspection, small cone ants from the genus Dorymyrmex were crawling over them, grooming their bodies without aggression from the larger ants. Moffett initially thought it was an attack but observed the harvester ants approaching cone ant nests first to solicit the cleaning. “Given the usual tendencies of ants, I first assumed that I was observing aggression,” Moffett said. “But the larger ants seemed to seek the attention of the smaller ants by first visiting their nests and then allowing the small ants to lick and nibble all over them.” Over several days, Moffett photographed at least 90 such interactions. A harvester ant would stand tall near a cone ant nest, prompting one or more small ants to climb aboard and groom for 15 seconds to over five minutes, even inside the jaws. The larger ants remained passive, shaking off the cleaners afterward. Cone ants ignored dead harvester ants nearby. “This new ant species is the insect equivalent of cleaner fish in the ocean,” Moffett said. “The potentially dangerous harvester ants even permit the visitors to groom between their open jaws.” Researchers suggest cone ants may feed on seed fragments removed from the harvesters, while the larger ants benefit from thorough cleaning of hard-to-reach areas. The cone ants represent an undescribed species. Moffett emphasized that such discoveries underscore the unknowns in nature. The findings appear in Ecology and Evolution (2026; 16(4), DOI: 10.1002/ece3.73308).