Ants in Lawns

There are many species of ants which occur in lawns and other turfgrass areas. Most ants do not require controls and are considered beneficial. However, ants may become a nuisance by constructing mounds or small hills in the lawn or by invading the home from the yard in search of food. The ants found in Iowa lawns are not biting or stinging pests. The fire ants of the southern U.S., well known for their aggressive behavior and painful stings, are not present in Iowa. Also, the noted mound building ants of the eastern U.S. that build ant hills several feet in height are not found in Iowa, although our local ants may build mounds several inches high and 12 to 18 inches in diameter if left undisturbed for a long period of time.

Ants are social insects that live in well-organized colonies. Nearly all of the ants in a colony are the wingless sterile females, called workers, typically seen on or around an ant hill. They do the work of the colony which includes enlarging and maintaining the nest, caring for the queen's offspring (larvae that reside within the nest) as well as search for food and bring it back to the nest. In the spring or fall ant colonies may produce winged males and females called swarmers. These disperse from a well established nest to begin new colonies.

Ant Mounds. Soil nesting ants construct mounds or small hills by bringing granulated soil to the surface from the nest below. These mounds may be unsightly, may cause lawn unevenness, and if large, may smoother out the surrounding grass.

Avoiding some of the worst ant hill activity may be possible by raking flat, on a regular and frequent basis, ant hills that appear above the grass tops during periods of prolific ant nesting activity (such as during periods of wet spring weather). If necessary, you can spot treat ant hills with insecticide. Rake the ant hill flat and sprinkle insecticide granules onto the soil surface or drench the mound area with a liquid insecticide. Use insecticides labeled for ant control outdoors and follow all labeled directions. Read and carefully follow instructions on the insecticide label. If granules were used, rake the area lightly after application and sprinkle with water. Keep children and pets away from the treated area until the grass has dried. General lawn treatment specifically for ant colonies is seldom necessary. For more information on outdoor use insecticides please read this article.