<P> The red imported fire ant (Solenopsis invicta), or simply RIFA, is one of over 280 species in the widespread genus Solenopsis . It is native to South America but it has become both a pest and a health hazard in the southern United States as well as a number of other countries . </P> <P> In the 1930s, colonies were accidentally introduced into the United States through the seaport of Mobile, Alabama . Despite earlier views that cargo ships from Brazil docking at Mobile unloaded goods infested with the ants, recent DNA research confirmed that the likely source population for all invasive S. invicta in the United States occurred at or near Formosa, Argentina, and virtually every analysis ruled out all sampled Brazilian populations as a potential source . Biologist E.O. Wilson says that he reported the first colony, in the Mobile area, when he was 13 . The ants then spread from Alabama to almost every state of the American South, from Texas to Maryland and a few other Mid-Atlantic states . Since the 1990s infestations have been reported in New Mexico and parts of Arizona in the Southwest . They have also been reported in California in the West, but probably arrived via ship or truck rather than by spreading . In a similar way, the ants were accidentally introduced into Australia in 2001 . </P> <P> In the United States, RIFAs have gradually spread north and west despite intense efforts to stop or eliminate them . As of 2011 in the United States they were found in most of the southern states: Alabama, Arkansas, Arizona, California, Delaware, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, New Mexico, Oklahoma, South Carolina, Tennessee, Texas, and Virginia . The U.S. Department of Agriculture also lists the entire island of Puerto Rico as infested . </P>

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