Recent rains expose fire ants 08-20-07

With the past several weeks of hot dry weather fire ants have gone unnoticed in my lawn until the recent showers have exposed their newly formed mounds. This has been a reminder that I have not applied my midsummer bait to keep them in check. Fire ant control is a never-ending battle across Mississippi, but with a good strategic plan and persistence you can keep them to a minimum in your lawn.

There are several methods of applying products that control fire ants, such as mound drenches, dry mound treatments, or broadcast sprays or granules. Probably one of the most effective for homeowners in terms of costs and effort is granular baits applied three times a year (spring, mid-summer, and fall). Baits can be applied to individual mounds, but when broadcast across the entire lawn you also eliminate small undetected colonies that quickly replace the larger ones you individually treated.

The insecticides, or growth regulators, used in baits are intended to be slow acting so that foraging ants will carry the product back to the mound where eventually the entire colony including the queen will be affected. Application rates for baits is generally only about 1 to 1.5 pounds per acre and needs to be applied when the ground is dry, ground temperatures are relatively warm, and there is no forecast of rain for a couple of days. Since these ants are great foragers, it is not critical that the baits are precisely spread like fertilizer or herbicides as long as they are distributed to all parts of the lawn. When treating individual mounds do not place the bait directly on top of the mounds, but broadcast it several feet away.

Baits can provide 80 to 90 percent control when applied two to three times a year. Therefore, if you are like me and haven’t put out a summer application, yet, you still can do so and with one more application just before winter, should provide excellent control.

If you have large colonies that need immediate reduction, then individual contact insecticide mound treatments can be used in combination with baits, but wait at least a few days to allow the workers to bring the baits into the mound.

There are many trade name baits available containing at least one of the following active ingredients: hydromethylon, fenoxycarb, spinosad, pyriproxyfen, methoprene, or abamectin. Since baits generally use some type of oils for attracting ants, it is important to use fresh baits and store them in cool dry areas so they don’t become rancid.

Extension publication #2331 Control of Insect Pests in and Around the Home Lawn provides additional information on fire ant control and other home lawn insects.

Published August 20, 2007

Dr. Wayne Wells is an Extension Professor and Turfgrass Specialist. His mailing address is Department of Plant and Soil Sciences, Mail Stop 9555, Mississippi State, MS 39762. wwells@ext.msstate.edu