Red imported fire ant

The red imported fire ant (Solenopsis invicta), or simply RIFA, is one of over 280 species in the widespread genus Solenopsis. Although the red imported fire ant is native to South America, it has become a pest in the southern United States, Australia, Taiwan, Philippines, and the southern Chinese provinces of Guangdong, Guangxi, Fujian and Hong Kong. There are also reports of ant hills in Macau, the former Portuguese enclave that borders the province of Guangdong. RIFA are known to have a strong, painful, and persistent irritating sting that often leaves a pustule on the skin.

In the 1930s, colonies were accidentally introduced into the United States through the seaport of Mobile, Alabama: cargo ships from Brazil docking at Mobile unloaded goods infested with the ants. 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. Since the 1990s infestations have been reported in New Mexico 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.
From : wikipedia