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. 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. They have since spread from Alabama to almost every state of the American South, from Texas to Maryland. Since the 1990s, infestations have been reported in California in the West and New Mexico in the Southwest, but probably via ship or truck (rather than overland migration) in the case of California.

RIFA are more aggressive than most native ant species and have a painful sting. A person typically encounters them by inadvertently stepping into one of their mounds, which causes the ants to swarm up the person's legs, attacking en masse. The ants respond to pheromones that are released by the first ant to attack. The ants then sting in concert, often inflicting death on smaller animals by overloading their immune systems.

California Dept. of Food and Agriculture, Plant Health & Pest Prevention Services (PHPPS), Pest Detection/Emergency Projects (PDEP), RIFA