fire ant

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various ants of the genus Solenopsis that build large mounds and can inflict a painful sting, especially S. invicta, native to South America and naturalized in the southern United States.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any of several red or yellow North American ants, of the genus Solenopsis, that can inflict a harsh sting.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun omnivorous ant of tropical and subtropical America that can inflict a painful sting