Where Fire Ants Are Found and How Their Range Spreads

Where Fire Ants Are Found

Fire ants are found across a wide swath of the southern United States, stretching from Texas and the Gulf Coast up through the Carolinas and as far north as Oklahoma and parts of Virginia. They are also well established in Puerto Rico and have been detected in isolated areas of California and New Mexico. Outside the U.S., fire ants have invaded Australia, China, Taiwan, the Philippines, and several Pacific island nations including Hawaii, where they continue to spread.

Most people first encounter fire ants in open, sunny habitats like lawns, pastures, golf courses, and field edges. They build large, flat mounds in soil and are especially common in areas with warm, humid climates that provide both moisture and plenty of insects or seeds to eat.

Native Range and Invasion History

Red imported fire ants (Solenopsis invicta) and black imported fire ants (Solenopsis richteri) are native to the floodplains of the Paraná River basin in South America, covering parts of Brazil, Argentina, Paraguay, and Bolivia. They arrived in the United States in the 1930s, likely through the port of Mobile, Alabama, in soil used as ballast on ships. From there, they spread outward along highways and waterways, aided by the nursery and landscaping trade, flood events, and human movement of infested soil and mulch.

Climate and Habitat Preferences

Fire ants thrive in warm regions where winter temperatures rarely drop below about −10 °C (14 °F) for extended periods. In the U.S., their range is bounded roughly by the southern tier of states, but individual colonies can survive in colder areas during mild winters. They prefer open, disturbed ground and avoid dense, shaded forests, though they can nest along forest edges and in abandoned fields.

How Their Range Continues to Expand

Fire ants keep moving into new territory through several pathways. Floodwaters carry entire colonies downstream, and queens can float on rafts of their own workers until they reach dry land. Human activities such as hauling sod, nursery plants, and construction equipment move colonies into uninfested counties and states. Climate change may gradually push the northern and western edges of their range further as winters warm.

What to Do If You Find Fire Ants

If you find fire ants on your property, act quickly to reduce stinging risk and limit their spread. Treat individual mounds with approved insecticide or bait products early in the season before queens establish new colonies. Avoid moving soil, mulch, or potted plants from infested areas to clean sites. In heavily infested lawns, a combination of broadcast bait treatments and targeted mound drenches works better than either method alone.