It is possible to control fire ants organically. Gardeners and homeowners have several organic treatment options that are quite effective. Many of these contain the active ingredient spinosad. Spinosad is a bio-pesticide produced through commercial culture of a soil-born microbe that produces metabolites toxic to certain insects. These metabolites are harvested and formulated into insecticide, so the final product contains no living microbes. But note that not all products that contain spinosad are completely organic; some contain non-organic inert ingredients. Spinosad products approved for organic production usually indicate so on the label. Organic fire ant control products containing spinosad are available as baits and as liquid drenches.

Organic Fire Ant Baits: Most organic fire ant baits contain spinosad as the active ingredient. Greenlight Fire Ant Bait with Conserve and Safer Fire Ant Bait are two examples. Baits are best used by broadcasting them over the entire yard according to label directions. Spinosad-based fire ant baits are relatively fast acting and should give results within two to three weeks. Depending on the level of control you expect, you may need to treat two to three times a year.

Organic Mound Drenches for Fire Ants: There are several organic insecticides labeled for use as fire ant mound drenches. The most common contain spinosad or d-limonene. Two examples of liquid spinosad products are Monterey Garden Insect Spray and Ferti-Lome Borer, Bagworm, Leafminer and Tent Caterpillar Spray. These products are used primarily to control caterpillar pests in home gardens and landscapes, but they also have directions for use as mound drenches for fire ants. D-limonene is an extract of citrus peels that has contact activity on certain pests, including fire ants. Orang Guard and Safer Fire Ant Killer are two examples of mound drench products containing d-limonene.

Apply mound drenches by mixing the specified amount of insecticide per gallon of water and drenching the fire ant mound. The ants are killed by contact activity. The amount of drench needed depends on the size of the  mound. Not using enough drench to thoroughly soak the mound is the main reason for control failures.

Use Both Baits and Drenches: One of the most effective ways to control fire ants with these organic treatments is to use the baits as the foundation of your control program and use liquid drenches to spot treat mounds that survive the bait treatments or that “pop up” between bait treatments.

Rebecca Bates is director of the Lincoln County Cooperative Extension Service. To contact her, call 601-835-3460.