Species of Fire Ants in the United States

Fire ants in the United States are broadly categorized into two groups – imported fire ants and native fire ants.

Imported fire ants

The most commonly encountered imported fire ant is the red imported fire ant, or Solenopsis invicta, also known as RIFA for short. Red imported fire ants pose the most serious medical threat from stinging. RIFA was accidentally imported into the United States through the ports of Mobile and Pensacola in about 1933.

Since those introductions, we have learned of the ant's extreme aggressiveness, painful sting, high levels of reproduction, few natural predators and its ability to survive dramatic temperature swings and severe weather. The RIFA is so capable of dominating insect populations within their habitats that they often displace other ant species. In order to combat RIFA, ant control experts have developed many effective types of bait, other chemical products and have introduced natural biological control methods such as predacious flies. RIFA is distributed in the southeastern states from North Carolina through Texas, plus the states of New Mexico and California

In 1918, black imported fire ants, or Solenopsis richteri, were also accidentally brought into the port of Mobile. It wasn't considered a different species from the RIFA until 1972. This non-native ant species has a limited range in parts of Mississippi, Alabama, Georgia and Tennessee.

Native fire ants

Although native fire ants aren't as hostile as imported fire ants, native species inflict just as much pain. The following are the known native fire ants in the United States.

Native southern fire ants

Solenopsis xyloni. Southern fire ants closely resemble red imported fire ants but can be distinguished from RIFAs by their brown to black color. The southern fire ant is widespread throughout the southern U.S. from Texas to North Carolina and the southwestern states, including California and Hawaii.

Tropical fire ants

Solenopsis geminata. Benefitting greatly from human commerce, these ants are found nearly worldwide. Preferring open spaces, tropical fire ants can easily overtake homes and farms in hot climates. Its distribution is found from Texas to Florida and South Carolina.

Desert fire ants

Solenopsis aurea and

Solenopsis amblychila. Their distribution is the southwest portions of the United States.

Solenopsis amblychila has been found in Arizona, west Texas, and in the Doña Ana Mountains of southern New Mexico at elevations from 5,000 to 8,250 feet.

Solenopsis aurea inhabits the Southwestern United States and is found below elevations of 6,600 feet.

Little fire ants

Wasmannia auropunctata. The little fire ant is a very small ant that is often transported by humans around the world. This ant is well established in the southeastern states and in Hawaii, plus has been reported to occur in Los Angeles County, California. Little fire ants are often seen in greenhouses in many areas where they occur. Because the workers move incredibly slow, their presence often goes undetected until their painful stings are felt. Fortunately, little fire ants aren't known for gathering en masse to form stinging swarms.