By Dan Gill
LSU AgCenter Horticulturist
Fire ants inflict painful stings and create unsightly mounds in our landscapes, so most of us would be happier if there were no fire ants around. It’s interesting to note, however, that fire ants are excellent predators and help control such pests as fleas and ticks in lawns.
Although eradicating the fire ant in Louisiana is about as likely as doing away with the mosquito or the cockroach, with persistence and the correct application of insecticides, fire ants can be controlled. But no treatment will eradicate them from a yard permanently.
A variety of products and methods are available to effectively control fire ants. The product chosen is primarily determined by the situation and the preferences of the individual doing the treatment. When using a pesticide, always read the label carefully before you purchase it. Make sure you understand the directions and are comfortable with how to use the product and that it is appropriate for your situation.
Fire ant baits consist of an insecticide combined with a food material fire ants will eat. Foraging ants bring the bait back to the colony and feed to other ants, including the queen. You can apply bait to individual mounds or, better, broadcast it over an entire yard. Even more effective than treating one yard, research done by the LSU AgCenter shows that if neighbors will get together and treat an entire neighborhood, the results are even better.
Use fresh bait, and apply it when the ground and grass are dry and no rain is expected for the next 24 hours. Apply baits when the worker ants are actively searching for food. You can buy a number of baits with a variety of active ingredients.
Some products, such as those containing acephate, are applied as a dry dust. Ants walking through the treated soil get the dust on their bodies and transport the insecticide into the mound. Within a few days, the entire colony should be killed. To use a dust, distribute the recommended amount evenly over the undisturbed mound.
Other insecticides used to control fire ants are mixed with water and then applied to the mound as a drench. These liquid mound drenches kill the ants underground, but they must be applied in sufficient volume to penetrate the entire nest. Generally, about 1 gallon of diluted mixture is poured gently over the top of each mound. These drenches usually eliminate mounds within a day.
Granular products offer another method of getting insecticide into fire ant mounds. To treat a single mound, measure the recommended amount and sprinkle it on top of and around the mound. Do not disturb the mound. If the label specifies to water in the granules, use a watering can to gently pour 1 to 2 gallons of water over the treated mound to wash the granules into the soil. Unless the product completely penetrates the mound, ants will move to a different site through underground foraging tunnels to avoid the insecticide.
A few active ingredients used in fire ant control products, such as boric acid, pyrethrin, rotenone, citrus oil extract and diatomaceous earth, are accepted by organic gardeners. Diatomaceous earth, a natural silica-based dust, will kill some ants, but it rarely eliminates ant colonies when used alone. Avoid breathing in the dust-like particles.
Pouring 2 to 3 gallons of very hot, almost-boiling water into the hill will eliminate about 60 percent of the mounds treated. But this treatment must be done carefully, or the person doing the treatment could be burned. Scalding hot water will also kill any grass and plants it contacts. Surviving mounds will need to be treated again.
Be advised that some home remedies don’t work well. Spreading grits on a fire ant mound will only feed them or make them move. Placing orange or grapefruit peel on a fire ant mound will only make the ants move to another spot. Shoveling one mound on top of another in an attempt to force the ants to kill each other is not effective.
The LSU AgCenter has an excellent free publication available called “Managing Imported Fire Ants in Urban Areas.” Hard copies may be available at your parish AgCenter office, and the publication is available online at www.lsuagcenter.com and putting “managing fire ants” in the search box.
The publication includes complete information about the problems fire ants cause and effective methods for how to control them. It also includes information on how to organize a community-wide fire ant suppression program as well as a complete listing of the types of fire ant insecticides and their modes of action and formulations, with generic names of active ingredients and some examples of product names.
With patience and correct application of pesticides, you can manage fire ants. Do not treat mounds until the soil temperature is 55 degrees or above, so that ants are actively foraging. Photo by Olivia McClure
Fire ants can be a nuisance, and they need to be controlled in lawns and gardens. But they do serve as predators and help control such pests as fleas, ticks and termites. Photo by Claudia Husseneder
This is a photo of the red imported fire ant from bugwood.org. Photo by Scott Bauer, USDA Agricultural Research Service