How Can I Stop Fire Ants?

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Conditions were ideal for fire ants to migrate into and spread throughout Catawba County in large numbers this summer. Fire ants are reddish brown and can be identified by their aggressive swarming behavior and their painful sting, which produces a small white, itchy bump on the victim within 8 to 24 hours. Imported fire ants (IFA) were accidentally introduced into the United States from South America about 70 years ago. They construct unsightly mounds and the ants can be significant pests to people, pets, and livestock. Their impact upon our lives can be minimized through patience and the use of integrated pest management (IPM) practices.

The most effective chemical control methods for imported fire ants results in queen mortality or prohibit her from producing more worker ants. Many ant baits and poisons are labeled for lawns and roadways. However, only a few baits are labeled for use in gardens and agricultural areas such as cropland, pastures, and orchards.
NCSU entomologists encourage using the two­step method for areas with a high IFA (Imported Fire Ant) mound density (over 20 mounds per acre) and low numbers of beneficial native ants. This method can effectively control heavy fire ant infestations when conducted at least twice yearly. The first step is to broadcast a bait formulated insecticide over the entire yard or agriculture land on a semiannual basis (spring and fall). The second step occurs seven to ten days later with the individual treatment of approved insecticidal dusts, liquid drenches, granules, or aerosols. If one has only a few mounds in the back yard, use the same theory but treat mounds individually.

Most fire ant bait is a combination of insecticide plus an attractive fire ant food (generally processed corn grits coated with soybean oil). Baits are taken into the colony by worker ants searching for food. The bait is distributed to other members of the colony through the exchange of food. One key to the efficiency of a bait is that the insecticide gets to the queen. Never put the bait directly on the mound. Instead, place bait two feet away from mounds (read the label directions).
Although many tradename pesticides are available for fire ants, the active ingredients can be divided into two main types: insect growth regulators (IGRs) and actual toxins. Hydramethylnon bait (active ingredient found in Amdro and Amdro Pro) is a toxin (slow­acting stomach poison) that disrupts the ant’s ability to convert food to energy. Indoxacarb (Advion, Spectracide Once and Done and Real­Kill Fire Ant Bait) is a fast acting toxin acting on the ant’s nerve cells resulting in paralysis and death. Hydramethylnon bait provide control from one to five weeks following treatment. Indoxacarb bait is the fastest acting bait, providing control in three to seven days following application. Fenoxycarb (Award) is an IGR that prevents queens from producing new workers. This bait takes from one to four months for control. Although an IGR may take longer to achieve results, control may last up to a year, especially if treated areas are greater than one acre. Extinguish Plus is a pre­blended combination bait containing both a slow­acting stomach poison (hydramethylnon) and an IGR (methoprene). This combination is fast­acting like hydramethylnon and long­lasting like methoprene.

Amdro Pro, Esteem, Extinguish, and Extinguish Plus are the only baits labeled for use on pastures and hay meadows. (All other pesticide tradenames for nonedible areas are listed only for examples.)
Baits can be applied with hand­held seed spreaders. For most baits 1 to 1 1/2 pounds per acre, or approximately 1 ounce per 2,000 square feet, is a recommended amount. For medium to large sized areas, chest type or vehicle mounted spreaders can be used. Broadcast treatments are less expensive (in terms of product cost and time) and control colonies even when mounds are not visible.

For best results:
1) Use fresh bait, preferably from an unopened container or one that has been tightly sealed and not stored long.
2) Do not disturb mounds before bait application.
3) Apply bait when the ground and grass are dry and rain is not expected for the next 12 to 24 hours.
4) Apply bait when foraging ants are actively searching for food. Try a greasy chip near an active mound. If ants are seen on it within 10 to 30 minutes, it’s a good time to apply bait. Ants are less active during cold and hot periods, when soil temperature is less than 70°F or greater than 95°F.

READ AND FOLLOW LABEL INSTRUCTIONS. Make certain the area you plan to treat with the bait product is listed on the label. Most bait products can be used in residential, recreational, and landscaped areas. However, only a few baits are labeled for use in agricultural areas, such as cropland, pastures, orchards, and vegetable gardens.

Take a look at this article for more information on fire ant reproduction: Fire Ant Morphology, Reproduction, and Development

For more information, call the Cooperative Extension Office at 828-465-8240 and ask for the
Crop and Garden Extension Agent – George Place or
Small Farms and Local Foods Extension Agent – April Vigardt or
Forage and Livestock Extension Agent – Glenn Detweiler.