Soil-nesting ants are beneficial to the turfgrass ecosystem and their presence should not be needlessly discouraged. However, there are times when they create enough annoyance that it may be desirable to reduce their numbers in the yard or around the house.
The first nuisance situation that may justify treatment is when ants are nesting close to the house and are foraging for food indoors. Barrier or perimeter sprays on the foundation and to the lawn next to the house may reduce this invasion. Any turfgrass spray should work, but diazinon, Dursban and Sevin are specifically suggested.
The second situation where lawn ant control may be warranted is when our normal, run-of-the mill yard and garden ants get visions of grandeur and become mound builders. Ant mounds can be built by special species of ants known for this habit but it appears other ants can make sizeable dirt piles if conditions are just right. Mounds a few inches high and several inches across are common in home lawns. Fence rows, meadows, pastures and other areas are frequently the sites for mounds as tall as 18 inches and 12 to 18 inches in diameter. Fire ants have not been reported in Iowa, so there is little potential harm from approaching or leveling Iowa ant mounds.
Removing ant mounds in lawns.
I suggest the following procedure for eliminating ant mounds in lawns. First, rake the ant mound down level by spreading the dirt to the surrounding area. Wait several days to see if the ants rebuild the mound. If they do, you can chose to use an insecticide to reduce the population rather than fight the mound with repeated raking. After the mound has been raked level, sprinkle a small amount of diazinon granules or Sevin dust onto the area. Rake again to mix the insecticide into the dirt and then water the area. Hopefully one treatment will reduce the ant population sufficiently to make their presence tolerable for the remainder of the summer. If not, repeat as needed.
This article originally appeared in the August 12, 1992 issue, p. 139.