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Description 1/8 to ¼ inch long red ants. Fire ants build dome-shaped mounds up to 2 feet tall on open, disturbed land, such as pastures, agricultural fields, housing developments, and parks. Mounds do not have an opening at the center, as other anthills do, and tunnels may extend 3 to 4 feet underground.
Where they live These pests arrived in the United States from South America in the 1930s and are now found in 13 states and Puerto Rico. Scientists believe their range will ultimately extend into portions of Virginia, Maryland, Delaware, and possibly even Washington State.
Why they're a problem Prolific and aggressive, fire ants kill newborn domestic animals and wildlife (especially ground-nesting birds), injure livestock, damage crop seeds and seedlings, outcompete native ants for resources, and inflict pain on humans and pets. Fire ants feed on insects, spiders, earthworms, and carrion but eat sugary or oily foods when available, which is why you sometimes find them indoors.
Organic damage control No current treatment (including chemical pesticides) eradicates fire ants from an area forever, but some eliminate existing colonies and can keep new ones from forming for up to a year. "The least-toxic, most cost-effective way to eliminate fire ants is the 'Texas Organic Two-Step,'" says Bastiaan "Bart" Drees, Ph.D., of the Texas Imported Fire Ant Research Center, in College Station, Texas. Overuse of any pesticides, even organic ones, diminishes their effectiveness, so before you use this method, determine which mounds on your property pose a threat to people and animals, and which can be simply avoided.
Step 1. In fall, before the first frost, broadcast a bait containing spinosad, a compound developed from a naturally occurring soil bacterium. Spinosad is sold under the trade name Conserve and is contained in Justice, Bull's Eye Bioinsecticide, and Green Light Fire Ant Control. The ants bring the bait back to the mound, and over a period of weeks, the colony dies off. Repeat this step in spring if you see mounds developing.
Step 2. Treat individual mounds as needed with a drench containing d-limonene, an extract of orange oil. D-limonene is sold as Citrex Fire Ant Killer, Safer Fire Ant Killer, and Orange Guard for Fire Ants. Follow the manufacturer's usage directions for any products containing either spinosad or d-limonene. The Organic Materials Review Institute (OMRI) has approved both as acceptable for use in organic agriculture.
Most home remedies for killing fire ants don't work; some are downright dangerous. Go to the article Fire Ant Controls for a leading researcher's review of available remedies and a report on the newest biological fire ant controls being tested by scientists across the southern United States.
