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How to Control Fire Ants in the Lawn

Fire ants are a nuisance and a painful, dangerous pest to anyone unlucky enough to live in their region.

While there are several species of fire ants found throughout the U.S., the red imported fire ant that has invaded the South is quite possibly the worst of all. Their painful bite, aggressive swarming behavior, and ability to form floating rafts to survive floods have made the red imported fire ant a nuisance throughout the South. You can find their mounds in gardens, yards, parks, playgrounds, golf courses, and pastures throughout the South.

What Are Red Imported Fire Ants?

Red imported fire ants entered the United States through Alabama from South America in the 1930s. They thrive in warm, humid climates and have gradually spread throughout the Southeast. They are small, reddish brown ants, about ¼ inch in length. They build large nests in the ground with mounds that can range from a few inches to 2 feet in height. Occasionally, fire ants will even move into homes during heavy rains or excessive drought. Fire ants can be especially troublesome in undisturbed pasturelands, where you can usually find numerous large mounds.

The Fire Ant Colony

Fire ants like to build mounds in open, sunny areas like lawns.

You'll often find mounds next to sidewalks and driveways that absorb and give off heat. In well-maintained lawns, fire ant mounds are rarely more than a few inches tall. However, a lack of mounds in your yard does not mean there are no fire ants present. Fire ants create elaborate underground tunnels that can extend up to 25 feet away from a mound. During periods of drought or extreme heat, they will tunnel deeper into the ground and not create mounds. A fire ant colony can have over 200,000 ants, including a queen who is solely responsible for laying eggs.

The Fire Ant Sting

The sting from a fire ant is something that you're not likely to forget anytime soon. Fire ants are known to attack threats to their nests in large numbers, which means not just one sting, but many at once. While their stings are painful and have a burning sensation, only a small number of people are allergic to them.

What To Do

Fire ants are most active when the temperatures range from 65 °F to 90 °F. The workers are most active outside the nest, scavenging for food in the cooler morning and evening hours. Controlling fire ants is a two-step process. First, use a mound treatment, like Ortho® Orthene® Fire Ant Killer1, to kill the nuisance mounds you see in your lawn and landscape beds. The key to success is to not disturb the mounds before treating them. When the mound is disturbed, the fire ants will aggressively swarm out of the mound while workers move the queen to safety - either deeper into the mound or into a satellite mound. Second, to kill the mounds in the lawn you don't see and to keep new mounds from forming, apply a broadcast fire ant killer, like Ortho® Fire Ant Killer Broadcast Granules. Or, if you have a St. Augustine, centipedegrass, or zoysiagrass lawn, Scotts® Turf Builder® Southern Triple Action, which will not only kill dollarweed and clover while it feeds your lawn, it will also kill and prevent fire ants for up to 6 months.