Fire ants are found throughout South America and the southern part of the United States of America. Two species of fire ants are native to the United States, while the other two species were brought to the United States as invasive species.
There are two species of fire ants that are native to the southern part of the United States: the tropical fire ant (Solenopsis geminata) and the southern fire ant (Solenopsis xyloni).
There are also two species of imported fire ants that arrived in the United States in the ballast soil from ships. The first to arrive was the black imported fire ant (Solenopsis richteri), which arrived in Mobile, Alabama, in 1918. The native range of these ants includes northern Argentina, Uruguay and southern Brazil. Now this species also lives mostly in Mississippi, Alabama and southern Tennessee.
The other invasive fire ant species is the red imported fire ant (Solenopsis invicta) which arrived in the late 1930's. The red imported fire ant is much more aggressive than the black imported fire ant, and it quickly pushed the black ants out of much of their range. Currently the red imported fire ant is classified as an invasive species throughout the southern part of the United States and in Puerto Rico.