Ants will feed on almost any organic material, including other insects, animals and plants. Ants usually venture into your flower bed seeking warmth and moisture. Several species of ants infest gardens in the United Sates, but red ants causing a problem in your flower beds are typically imported fire ants (Solenopsis invicta), which have become an aggressive and annoying pest.
Red imported fire ants are red to dark brown in color, and range in size from 1/8 to 1/3 inch long. Red imported fire ants live in colonies with a queen, building mounds that resemble gopher holes or crumbly piles of earth. They prefer to build in open areas with sunlight, grass and moisture but they may burrow under paving stones, rotting wood, within walls, or inside tree trunks. You may also find them along driveways, beside flower beds, or near trees, mail boxes and fences. Their aggressive behavior distinguishes red imported fire ants from other species. Rather than scurry away when disturbed as other ants will do, red important fire ants aggressively attack anything touching their mound or disturbing their activity.
Red imported fire ants go to flower beds looking for food. Their feeding can harm delicate plants, and red ants may protect insect pests, such as aphids that secrete honeydew, a sweet substance ants like to eat. In addition to the feeding damage, red imported fire ants attack any disturbance to their food or colony by biting or stinging their perceived attackers. Their sting is painful, and the venom causes a burning sensation around the bite area. Their nesting may also damage plants, lawns and electrical fixtures.
You may prefer to avoid chemicals whenever possible. Boric acid and diatomaceous earth will kill most ants that are foraging in your flower beds, but their effectiveness is limited when attempting to kill entire colonies and you should not spread boric acid on soil. You can also use products containing plant-derived insecticides such as rotenone, nicotine sulfate and permethrins. However, these products must contact and kill the queens to gain control over the colonies so total eradication often requires several applications. Home remedies, such as soap solutions or wood ashes, are not usually effective at killing red imported fire ant colonies.
Control of severe infestations of red imported fire ants often requires using chemicals. Insecticides that control red imported fire ants are available in the form of granular baits and poisons or liquids. Bait insecticides work by letting the ants carry the poison back to the nest and the queen. Place them in areas where the ants move about, such as along your flower beds, and also on and around the ant mound. Granular ant baits and poisons are usually broadcast over an area at a rate of about 1 1/2 pounds per acre. Wait two to three days before attempting any other chemical control method. Liquid insecticides work as contact poisons, and are poured into the mound and on the soil around the mound. The soil must be soaked thoroughly with the solution. Baits and insecticides containing hydramethylnon, spinosad, methoprene and fenoxycarb can be effective in controlling red imported fire ants. Always read and follow the label directions on all pesticide products. Store them away in locked cabinets or sheds, safely away from food, feeds and out of the reach of children and pets.
- University of Tennessee: Imported Fire Ants in Tennessee
- University of California Extension: Red Imported Fire Ant
- North Carolina State University Cooperative Extension: Managing Fire Ants
- University of Florida Extension: Imported Fire Ants on Lawns and Turf
- Purdue University Cooperative Extension: Managing Imported Fire Ants in Urban Areas