Fire ants can ruin picnics and football games year-round, but treating fire ant colonies in the fall can help edge out future colonies.
“Fire ant colonies have been growing through the summer and have reached their peak size,” said Dan Suiter, a Cooperative Extension entomologist with the College of Agricultural and Environmental Sciences. “Attacking those colonies now will help next spring when they start to swarm again.”
Fire ants are easier to kill in the fall, he said, for four main reasons.
First, they’re more active. That makes it easier to treat them with fire ant baits.
Second, in the cooler weather of fall, fire ants aren’t too deep in the ground. That makes them easier to kill with a mound-drench, granular, dust or aerosol contact insecticide.
Third, in the fall, you’re treating when many fire ant colonies are very young. Fire ants mate all year long, but they’re most actively mating in the spring. Mated queens fly away and establish new colonies. By fall, these colonies are well established but still fairly small.
Fourth, and the thing that makes fall the single best time to treat fire ants, Suiter said, is that it’s followed by winter. Extreme cold is tough on fire ants.
Baits take a long time to work. They weaken colonies and make them less able to respond to the challenges of winter weather.