When you think of fire ants in the fall, “vulnerable” isn’t the
first word that pops into your
mind. But it should be.
“If I could treat fire ants only once a year, I’d do it in the
fall,” said Beverly Sparks, a
University of Georgia scientist.
Fire ants are easier to kill in the fall for four main reasons,
said Sparks, an Extension Service
and research entomologist in the UGA College of Agricultural and
Environmental Sciences.
First, they’re more active. That makes it easier to treat them
with fire ant baits.
“You can use fire ant baits any time of the year. But they’re
most effective when the ants are
actively foraging for food,” Sparks said.
Fire ants are most active in spring and fall, when daytime
temperatures are between 70 and 85
degrees, she said.
“Actively foraging ants will pick up a bait and carry it into
the nest within minutes,” she said.
If the ants are inactive and don’t find the bait quickly, it
will become rancid. By the time the
ants find it, it no longer appeals to them.
The second reason fire ants are vulnerable in the cooler weather
of fall is that they’re not too
deep in the ground.
That makes them easier to kill with a mound-drench, granular,
dust or aerosol contact
insecticide. When you use those products, Sparks said, “it’s
critical to treat when the queen
and brood are close to the surface.”
Another advantage unique to the fall is that you are treating
when many of the fire ant colonies
in your yard are very young.
“Fire ants mate all during the year, but they’re most actively
mating in the spring,” Sparks
said. Mated queens fly off and establish new colonies. By fall,
these colonies are
well-established but still very small.
“Quite often you don’t even know they’re there,” she said. “But
if you don’t treat them,
they’ll become the big mounds you see next year.”
How do you treat them if you don’t know where they are?
Broadcast a fire ant bait.
That’s the first step in the ongoing program Sparks recommends
for fire ant control. Use a
fresh bait, she said, and apply it by the label directions. Then
treat individual problem mounds
with an approved contact product. The final step is simply to
repeat the first step once or twice
a year.
The one thing that makes fall the single best time to treat fire
ants, Sparks said, is that it’s
followed by winter.
Extreme cold is tough on fire ants, she said. That makes baits
even more effective in the fall.
“Baits take a long time to work,” she said. “They weaken
colonies and make them less able to
respond to the challenges of winter weather.”
The young colonies are especially vulnerable, she said, because
they don’t have many
workers. So they can’t respond very quickly to the need to
escape freezing temperatures.
The networked tunnels of a fire ant mound are constantly
collapsing, she said. Moving deeper
into the ground requires a lot of work. Anything you can do to
reduce the number of ants
available to gather food and maintain the mound structure makes
the colony less able to
survive winter weather.
“Winter is an ally in controlling fire ants,” Sparks
said. “Reducing their numbers in the fall
can help push them over the edge in the winter.”
