Fire ants are most vulnerable in the fall

If you have been battling fire ants this summer, you are about to see them get even worse as the weather cools down.

If we get a good bit of rain, you'll see even more mounds pop up around the landscape.

The good news is that fire ants are easier to control in the fall.

You can use fire ant bait any time of the year but they're more effective when the ants are actively foraging for food, typically in the spring and fall when daytime temperatures are between 70 and 85 degrees.

Treat your yard late in the day when it is dry and rain is not forecast for at least 24 hours. Baits eliminate 80 to 95 percent of mounds.

After the bait is on the ground, foraging ants will quickly pick it up and carry it into the nest. 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 in the fall is that their mounds are shallow, which makes them easier to kill with a mound drench, granular, dust, or aerosol contact insecticide.

Another advantage unique to the fall is that you are treating when many of the colonies are very young.

Fire ants mate all year but they're most active in the spring. The mated queens fly off and establish new colonies. By fall, colonies are well established but still small. Quite often you don't even know they're there unless we get a lot of rain to bring the mound up and out of the ground. But if you don't treat them now, they will become big mounds by next year.

Young colonies also are vulnerable because they don't have many worker ants, so they cannot respond quickly to the need to escape freezing temperatures in winter.

The network of tunnels of a fire ant mound is constantly collapsing. 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 makes the colony less able to survive.

Baits are by far the most economical option if you have a yard of an acre or more. Baits fall into two basic groups; those with active ingredients that are toxic to ants (such as Amdro) and those that have as active ingredients growth regulators that sterilize the queen and stop development of the immature ants in the colony.

It takes about six months for a colony of ants to grow from the founding queen to a size where there are enough workers to build the characteristic mound. Baits are good at breaking that cycle. There will be ants between these applications, just not all that many.

For smaller areas, or where you need zero ants, use a broadcast application of a contact insecticide.

Over 'N' Out (active ingredient: fipronil) remains the best overall product providing season-long control, but it is best when applied in the spring.

The next best after Over 'N' Out are those with pyrethroids as active ingredients. Pyrethroids are active ingredients ending in "thrin" such as bifenthrin, permethrin, cypermethrin or cyfluthrin.

While Over 'N' Out will usually give season-long control of ants, pyrethroids are not as long-lasting, but will usually give from one to four months of control. After that, the cycle starts over when the ants start flying, which they do in any season except winter.

Reach Sid Mullis, the director of the University of Georgia Extension Service Office for Richmond County, at (706) 821-2349 or smullis@uga.edu.