Red imported fire ants are a destructive pest commonly found across the US South and Southwest. Their presence is easily identified by dome-shaped mounds of loose soil that lack a central opening. These aggressive insects are known for their painful, burning sting, and colonies can grow rapidly, sometimes housing hundreds of thousands of ants and multiple queens. Effective control is necessary for personal safety and to prevent damage to lawns and electrical equipment.
Before You Begin: Safety and Preparation
Before approaching a fire ant mound, precautions are necessary to avoid painful stings. Workers quickly emerge and attack when the mound is disturbed, so wearing closed-toe shoes, long pants, and protective gloves is recommended. Since ants run up vertical surfaces, tucking pant legs into socks adds an extra layer of protection.
Timing the treatment maximizes effectiveness. Fire ants are closest to the surface and most active during cooler parts of the day, typically in the early morning or late evening. Foraging activity can be tested by placing a small food item, such as a potato chip, near the mound and observing if ants are attracted within 30 minutes. Never disturb the mound before applying treatment, as this causes the colony to immediately move deeper underground or relocate entirely.
Chemical Treatments for Immediate Eradication
The most effective strategy for widespread control is the “two-step method,” which combines a broadcast treatment with individual mound applications. The first step involves broadcasting a slow-acting insecticide bait over the entire infested area using a hand-held spreader. Foraging worker ants collect these granules, typically corn grits coated with soybean oil and a slow-acting poison, and carry them back to the nest to feed the queen and other colony members. This method is efficient because the ants distribute the poison throughout the colony, eventually killing the queen and achieving 80% to 90% control over several weeks.
The second step targets individual mounds that require immediate elimination, such as those in high-traffic areas or next to a home foundation. Liquid mound drenches use a fast-acting insecticide, such as permethrin or acephate, mixed with water and poured directly onto the mound. Success depends on using enough liquid (generally one to two gallons for small to medium mounds) to thoroughly soak the entire underground network and reach the queen. Always follow the product label instructions precisely, as using too little drench will only kill surface ants and cause the colony to relocate.
An alternative is a dry mound treatment, often containing acephate, which is sprinkled over the mound and kills the colony within a few days. For all chemical applications, the ground should be dry, and no rain should be expected for 24 to 48 hours to ensure the product remains effective. This targeted approach saves money and reduces the amount of pesticide used in the environment.
Non-Toxic and Natural Control Methods
For those who prefer to avoid chemical pesticides, boiling water is a proven method for eliminating a fire ant colony. Pouring two to three gallons of almost boiling water directly into the center of the mound will kill the colony about 60% of the time by physically cooking the ants. This technique offers an instantaneous effect without leaving residual toxins. However, the hot water will also kill any surrounding grass or vegetation it contacts.
Diatomaceous Earth (DE) is another non-toxic option, working as a mechanical insecticide. This fine powder is made of the fossilized remains of tiny aquatic organisms whose sharp edges scratch the ant’s protective outer layer. The abrasion causes the insect to lose moisture and die from dehydration. DE should be sprinkled directly on and around the mound when active, but it only kills ants that come into contact with it and rarely eliminates the queen deep within the colony.
Other popular home remedies, such as drenching a mound with dish soap or applying club soda or uncooked grits, are generally ineffective for complete colony eradication. These mixtures typically only kill ants on the surface, and the colony’s extensive tunnel system ensures the queen remains safely out of reach. The most reliable natural method involves using organic baits or drenches that contain ingredients like spinosad or pyrethrins.
Monitoring and Long-Term Prevention Strategies
After treating a fire ant mound, monitoring is necessary to confirm the colony has been eliminated. Return to the site two to three days after application to check for renewed activity or mound rebuilding. If the mound appears abandoned and no ants are present, the treatment was likely successful. If new activity is observed, a follow-up treatment is necessary. Sometimes, a surviving colony will simply move a short distance away and create a new mound nearby, a phenomenon known as “budding” or relocation.
Long-term prevention focuses on making the area less hospitable to fire ants. Maintaining a clean yard by eliminating piles of wood, leaves, and other debris removes potential nesting sites. Keeping the grass mowed and managing standing water also reduces the environment’s attractiveness. For ongoing protection, applying a granular broadcast treatment seasonally in the spring and fall helps control foraging workers and newly settled queens before they establish mature colonies.