A cluster of fire ants.
fire ant definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
any of a genus (Solenopsis) of ants whose sting causes a burning sensation, esp. a South American species (S. invicta) that has become a severe pest in the S U.S.
fire ant definition by American Heritage Dictionary
Any of several ants of the genus Solenopsis, especially S. geminata or S. saevissima of the southern United States and tropical America, that build large mounds and can inflict a painful sting.