Fire ants are present in Tennessee, including the destructive Imported Red Fire Ant (\(Solenopsis invicta\)) and the Black Imported Fire Ant (\(Solenopsis richteri\)), along with cold-tolerant hybrids of the two species. These aggressive insects pose a risk to public health due to their painful stings, as well as to agriculture and native ecosystems. Understanding their current distribution and characteristics is the first step in managing their impact.
Where Fire Ants Are Found in Tennessee
The distribution of imported fire ants has historically centered on the warmer, southern and western portions of the state. The infestation boundary is not static and has been steadily expanding, particularly due to hybrid species that exhibit greater cold tolerance. The Tennessee Department of Agriculture maintains a formal quarantine line to limit the movement of regulated items like soil, sod, and nursery stock from infested counties to non-infested areas.
This quarantine area encompasses a large number of counties, especially those bordering Mississippi, Alabama, and Georgia. Recent expansion has moved the line further north and east, including counties like Clay, Claiborne, Campbell, and Greene. The quarantine serves as a regulatory measure, acknowledging that the ants are established within these boundaries and requiring residents to take control measures themselves.
Identifying Fire Ant Mounds and Workers
Accurate identification begins with recognizing the distinct structure of the fire ant colony’s nest. Unlike the nests of many native ant species, a fire ant mound is dome-shaped and lacks a single, obvious central opening. Workers emerge from foraging tunnels located away from the mound, a feature that helps protect the colony’s interior.
The mounds can vary significantly in size, sometimes reaching 18 to 24 inches in height in undisturbed areas, and are quickly reconstructed, often after a heavy rain. The worker ants are polymorphic, meaning they vary in size within the same colony, ranging from 1/16 to 3/16 of an inch long. Their bodies display a reddish-brown coloration with a darker, shiny brown or black abdomen.
What Happens After a Fire Ant Sting
A fire ant sting is painful because the ant bites to anchor itself before injecting a potent alkaloid venom multiple times. The initial sensation is an immediate, sharp, burning feeling at the site of the sting. Within an hour, a small, red welt with a raised white center will form, which is a localized reaction to the venom.
The most distinctive sign of a fire ant sting is the formation of a sterile pustule, or a pimple-like blister filled with whitish or yellowish fluid, which typically develops within 24 hours. These pustules are intensely itchy and should not be scratched or broken, as this can lead to secondary bacterial infection and scarring. For basic first aid, washing the area with soap and cold water, applying a cold compress, and using an oral antihistamine or hydrocortisone cream can help manage the burning and itching.
A small percentage of individuals may experience a severe, systemic allergic reaction known as anaphylaxis, which requires immediate emergency medical attention. Symptoms of this life-threatening reaction include widespread hives, swelling of the tongue or throat, difficulty breathing, or dizziness. A severe reaction can progress rapidly, so anyone experiencing these symptoms should seek medical care immediately.
Controlling Fire Ant Colonies
Effective management of fire ant populations often employs a strategic “Two-Step Method” that targets both the foraging workers and the queen. The first step involves a broadcast treatment using a slow-acting granular bait insecticide spread over the entire infested area. Worker ants mistake the bait for food and carry it back to the colony, where it is shared with the queen, which is the ultimate target for colony elimination.
This baiting process is slow, often taking several weeks to months to achieve maximum colony control, but it effectively treats both visible and hidden mounds. The second step involves individual mound treatments using fast-acting contact killers, such as a liquid drench or dust, on any remaining mounds. Treatments are most successful when the ants are actively foraging, typically when the soil temperature is above 60 degrees Fahrenheit and the ground is dry, which often means applying in the late afternoon or early evening. For widespread or persistent infestations, professional pest control intervention may be necessary.