Solenopsis invicta

Definition

A highly invasive species of fire ant in the genus Solenopsis, subfamily Myrmicinae, native to South America and now established across multiple continents including North America, Australia, and parts of Asia and Europe. The species is notable for its polymorphic worker caste (variable worker sizes), aggressive territorial defense using venomous stings, and ecological dominance in disturbed habitats. Colonies construct large soil mounds with extensive subterranean tunnel networks; workers forage at distances from hidden nest entrances. The name *invicta* (Latin: "unconquered") refers to its resilient colonization ability.

Etymology

Latin *invicta* meaning 'unconquered' or 'invincible,' referencing the species' aggressive colonization and persistence

Example

In the southeastern United States, Solenopsis invicta has displaced native ant communities and become a major agricultural and medical pest, with its venom causing anaphylaxis in sensitive individuals.

Synonyms

• Red imported fire ant
• RIFA

Related Terms

• Solenopsis
• Myrmicinae
• Formicidae
• Polymorphism
• Invasive species
• fire ant
• Gaster
• venom
• colony
• supercolony

Usage Notes

The specific epithet is always lowercase *invicta*; the common name 'red imported fire ant' distinguishes this species from native North American fire ants such as Solenopsis geminata. The species was originally described as a variant of S. saevissima by Santschi in 1916, then elevated to species rank by Buren in 1972; the name S. invicta was preserved under priority rules despite later synonymy recognition. Not to be confused with Solenopsis richteri (black imported fire ant) or hybrid S. invicta × richteri populations.