By Faith Peppers
University of Georgia
"It's appropriate to treat for fire ants anytime that they're active," said Dan Suiter, an entomologist with the UGA College of Agricultural and Environmental Sciences. "They're active in warm months."
Since it stays warm well into the fall in the South, keep up the fight.
"You hear about fall treatments sometimes in light of baiting programs," Suiter said. "Many of the baits registered for fire ant control are very slow-acting growth regulators. It may take a half year or more to eliminate the colonies. So, the thinking is to bait in the fall, and the next spring the ants will not return."
New weaponsRed imported fire ants first made an appearance in Georgia in the early 1950s. By 1987 they had spread to 143 of 159 counties. Today the entire state is infested, as is much of the East Coast to southern Virginia.
"While the basic biology of fire ants hasn't changed, there have been some advances in control techniques and materials," said UGA entomologist Will Hudson.
"Baits remain the best options for large areas (more than 1 acre or so)," he said.
Many brands fall into two basic groups: those with active ingredients that are toxic to the ants (like Amdro) and those that have as active ingredients insect growth regulators that sterilize the queen and stop development of the immature ants in the colony.
"Baits work by taking advantage of the ants' behavior," Hudson explained, "so we can apply a small amount (1 to 1.5 pounds per acre) of material and let the workers take it back to the mound and feed it to the colony."
No mounds v. no antsApplied every six months, they often carry a guarantee of "no mounds" if applied correctly. Not "no ants," but "no mounds."
"As it happens, it takes about six months for a colony to grow from the founding queen to a size where there are enough workers to build the characteristic mound," he said, "and the baits are good at breaking the cycle. There will, however, be ants there between applications, just not all that many."
Bait treatments generally cost $20-30 per acre.
For smaller areas, or where you need zero ants, Hudson recommends a broadcast application of a contact insecticide.
"The best of these include fipronil products such as Over'n'Out for homeowners or those with pyrethroids as active ingredients," he said.
Pyrethroids are active ingredients ending in -thrin such as bifenthrin, permethrin, cypermethrin or cyfluthrin.
"There are lots of these on the shelves, as they're all off patent now," Hudson said.
"Fipronil will usually give a season of 'no ants,'" he said. "The pyrethroids are less long-lasting, but will give 1 to 3 or even 4 months of control. After that, the cycle starts over if the ants are flying (almost all year in south Georgia and April through October in Atlanta)."
Costs range from less than $50 per acre for pyrethroids to more than $150 per acre for fipronil. "But, if your yard is 5,000 square feet, they aren't that expensive," Hudson said.
A newcomer to the fire ant control market is indoxacarb, which is sold as Advion for commercial use and in the Spectracide line for homeowners. "It's a bait, but instead of weeks to see a reduction in ants, they start to disappear in a couple of days. It's still a 'no mounds' type, but fast," Hudson said.
(Faith Peppers is the director of public affairs with the University of Georgia College of Agricultural and Environmental Sciences.)