ALBANY - For years, experts predicted fire ants couldn't tolerate frosty winters in the north Georgia mountains. Well, the aggressive, fast-breeding South American pests have defied predictions.
Fire ants have now spread to all of Georgia's 159 counties and a new type discovered in the Rome area seems to be especially adept at hunkering deep in the ground to escape the cold, according to Wayne Gardner, a University of Georgia entomologist based in Griffin.
With no natural enemies outside of South America, fire ants have spread about 275 million acres in the past 80 years, mostly in the Southeast. Isolated colonies have also been found in Delaware, New Mexico and California. They've also turned up in Australia.
The aggressive predators, which crowd out native ants, live in the ground and build mounds above their colonies.
With their proclivity for attacking crops, wildlife and people, fire ant damage runs into the billions of dollars each year. They can kill newborn deer and quail hatchlings.
When disturbed, they swarm out of their nests and sting repeatedly, injecting their victims with venom that causes small sores. Their stings usually cause only pain and discomfort, but they can prove fatal to humans who are allergic to the venom.
There are two main types of imported fire ants: red and black.
The black type is believed to have arrived about 1918 at Mobile, Ala., in dirt that was used as ship's ballast. The red is believed to have arrived in Mobile the same way in the 1920s. The black spread to Mississippi and Alabama, while the red spread beyond to other states.
Before the discovery of fire ants in northwest Georgia's Floyd County, scientists had assumed they would not be able to survive in the northern third of the state, Gardner said.
But a Floyd County extension agent discovered fire ants in 1985. Then a U.S. Department of Agriculture Laboratory determined they were hybrids a cross between reds and blacks.
In 1998, there had still been no reports of fire ants in the mountainous Towns, Rabun, Habersham, Union and Lumpkin counties, in the mountains of northeastern Georgia. But now they have been seen in every county.
``Basically we were hit from two sides,'' Gardner said. ``It (the red fire ant) came from the southwest and moved across the state, but we also had this hybrid that moved in from Alabama into the northeastern part of the state. So it covered the state a lot quicker.''
The hybrids and the reds look identical, Gardner said. It takes a laboratory test to tell them apart.
``The hybrid behaves the same. It looks the same and it has all the same characteristics,'' Gardner said.
In tests, the reds and hybrids tolerate cold just about the same, so the hybrid may just have better survival instincts.
``The hybrid forms may have adapted some sort of behavior that allows them to survive when the temperature drops,'' Gardner said. ``Or they may travel farther underground than the red ants. We just don't know yet.''
There is no reliable way to eradicate fire ants, even though Americans spend millions of dollars a year on chemicals for temporary control. One fire ant colony can contain between 100,000 and 300,000 worker ants and each colony produces several hundred queens every summer. They fly off, mate in midair and establish new colonies.
USDA scientists have traveled to South America, where fire ants are kept in check by natural enemies, to identify biological controls that could be helpful in the United States. In the late 1990s, they released a disease that attacks the queens and weakens their colonies and two types of flies that decapitate fire ants.
``The nice thing about these biological control agents is that they self-perpetuate in the field,'' said David Oi, a research entomologist with the USDA's Agricultural Research Service in Gainsville, Fla. ``If they get established, I think they will help suppress the population. Eventually, we may have a suite of agents that will at least keep things down lower than they are now.''
Sunday
June 15th, 2025
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