Invasive fire ants migrating further north into Tennessee with 87 counties now infested by the stinging insects, including all the Upper Cumberland.
University of Tennessee Professor and Extension Urban Entomologist Karen Vail said the populations are growing to the point that residents are increasingly noticing the pests.
“For most people, you know, you’re standing in the yard,” Vail said, “You don’t realize you’re actually stepping into a fire ant mound, and the ants will emerge in large numbers all at once and run up your leg and then bite first, get a good grab onto the skin and then whip their abdomen around and inject that stinger.”
Vail said the ants are identifiable by their distinct dome-shaped mounds and specific physical characteristics like a two-segmented waist and a ten-segmented antenna. Vail said homeowners should monitor their lawns for these mounds, noting that the insects prefer open areas with grass rather than heavily wooded environments.
“For most people, say on average 97% of us, we’re just going to get that fiery burning sensation and we’ll have a pustule that forms,” Vail said. “For that 1 to 3% that are hypersensitive, they can go into anaphylactic shock where they get low blood pressure, they may pass out, they may have difficulty breathing due to the allergic response to the venom.”
Vail said the most effective treatment method for homeowners is using fire ant bait for individual mound treatments. Vail said if a property has more than 20 mounds per acre, it becomes more economical to broadcast the bait across the entire area.
“Those are the most threatened by fire ants is that hypersensitive population and then the very young and very old because of their inability to remove the ants quickly,” Vail said. “Only because they’re less able to get away from the fire ants and to remove the ants that are on them.”
Vail said the species is difficult to eliminate because winged reproductives can fly up to a mile to start new colonies. Vail said the ants are also accidentally transported through nursery stock, sod, earthmoving equipment, and hay that has been in contact with the ground.
“We can eliminate what’s on a property at one time, but then it’s—we still have to keep inspecting because we’ll have new fly-ins occurring,” Vail said. “Those newly-mated queens will land on a property and start the cycle over again.”
Vail said weather patterns influence how visible the ants are to the public. Vail said while the ants are more active in warm weather, they build up their mounds more clearly following rain when there is moisture in the soil.
“It is very hot, so the ants will not be foraging when it gets into the 90s,” Vail said. “They’ll be underground waiting for it to cool off just a little bit.”
Vail said the ants have been present in the state for decades but continue to expand their territory into new areas.
