Invasive ants from South American said displacing native U.S. species In 2012 the species was formally identified as Nylanderia fulva, which is native to northern Argentina and southern Brazil. Frequently referred to as Rasberry crazy ants, these ants recently have been given the official common name "Tawny crazy ants." Credit: Joe MacGown, Mississippi Entomological Museum AUSTIN, Texas, May 16 (UPI) -- Invasive "crazy ants" displacing native fire ants across the southeastern United States could have dramatic effects on the region's ecosystem, researchers say. The "ecologically dominant" crazy ants -- the latest wave in a history of ant invasions from the southern hemisphere -- are reducing diversity and abundance across a range of ant and arthropod species, scientists at the University of Texas at Austin reported Thursday. "When you talk to folks who live in the invaded areas, they tell you they want their fire ants back," UT researcher Ed LeBrun said. Fire ants are in many ways very polite. They live in your yard. They form mounds and stay there, and they only interact with you if you step on their mound. Crazy ants by contrast "go everywhere," he said, invading people's homes, nesting in crawl spaces and walls, becoming incredibly abundant and threatening damage to electrical equipment. Native to northern Argentina and southern Brazil, crazy ants were first discovered in the Unites States in 2002 by a pest control operator in Houston and have since established populations in 21 counties in Texas, 20 counties in Florida and a few sites in southern Mississippi and southern Louisiana. "They don't sting like fire ants do, but aside from that they are much bigger pests," LeBrun said. There are videos on YouTube of people sweeping out dustpans full of these ants from their bathroom. You have to call pest control operators every three or four months just to keep the infestation under control. It's very expensive.