The red imported fire ant (Solenopsis invicta) is indeed an invasive species in the United States, having been introduced in the 1930s. They are thought to have arrived through the port of Mobile, Alabama, likely in soil or plant material used as ballast in ships from South America, where these ants are native.
Since their introduction, red imported fire ants have spread rapidly across the southern United States and have established populations in many states, particularly in the southeastern regions. Their presence has led to various ecological impacts, including competition with native ant species, disruption of local ecosystems, and potential harm to wildlife.
Fire ants are well-known for their aggressive behavior and painful stings, which can pose risks to humans and pets. They build large mounds in open areas, which can be a nuisance in agricultural settings, parks, and residential yards. Efforts to control and manage fire ant populations include chemical treatments and biological control, but these methods can vary in effectiveness.
Overall, the introduction of the red imported fire ant has had significant ecological, economic, and social implications in their non-native range.