NORTH FLORIDA — Fire ants’ fondness of fall arouses a flurry of activity. And that renewed activity provides an opportunity to control this pesky insect. The thing that triggers the increase in fall fire ant activity is the mild temperature range.
Two main means of controlling fire ants work best when daytime temperatures range from 70°F to 85°F. That’s because the fire ants are closer to the soil surface and more active in that range.
When treating single mounds with a contact insecticide, it’s critical to treat when the queen and brood are close to the surface, which is between 70 and 85 degrees. When using any kind of fire ant bait, it’s best to put that out when the ants are foraging for food. They are most actively doing that between 70 to 85 degrees.
Be sure to follow all label directions on the product for best results.
Actively foraging ants will pick up a bait and carry it back into the nest within minutes. That’s important because the baits tend to quickly go rancid and then are no longer attractive to ants. So, if you put a bait out when it’s too hot, above 90°F, or too cool, below 60°F, it’s just going to sit there.
The window for treating fire ants during fall is narrow. As the fall deepens and winter comes on, temperatures may quickly dip below the ants’ ideal range. The ants move deeper in their nests and become less active.
The sudden appearance of large mounds in fall isn’t a sign of a fire ant population explosion. It’s mostly that the ants already there have become more active and visible. Rain has a great deal to do with that. In hot, dry weather, you don’t see much change in fire ant mounds.
When the weather cools, though, the ants become more active. Then, when it rains, the mounds seem to pop out of the soil and the fire ants bring the wet soil up out of the nest, building up the mound.
Mounds more than a foot high have been there close to a year or longer. The mounds of younger colonies will be much smaller.
Even though you probably will not kill one hundred percent of the fire ant nests you treat, the fall is an excellent time to reduce their numbers.
For more information on fire ants and their control, contact the UF/IFAS Extension Office in your County or use the following link to access an Extension publication on fire ants. https://edis.ifas.ufl.edu/pdf/LH/LH05900.pdf