Field ants are one of the most common ants seen outdoors, especially when they swarm in the fall to mate. Although they are harmless, the large numbers of winged ants emerging from their underground colony can be alarming―or just annoying, and warrant pest control.
The term "field ants" can refer to a variety of species of ants that inhabit fields, meadows, and lawns. They are often considered to be beneficial because they feed on other insects, including bed bugs, moths, silverfish, termites, and plant pests (such as aphids and mealy bugs). But, like any insect pest, when it invades your outdoor event or appears in large numbers, it can quickly become a problem.
Field Ant Problems
These ants will build mounds in lawns that can extend up to four feet in diameter. Although in some geographic areas, the field ant species build mounds that rarely rise higher than the height of the grass, in other areas, the mounds of these ants rise as high as two feet tall. They will also nest in firewood and other such piles, thus care should be taken when reaching into such areas or bringing firewood into the home. Field ants will also sometimes enter homes in search of food, but this is rare.
The large, tall mounds of field ants can destroy the appearance of the lawn and even make mowing hazardous. This damage is rarely long-lasting, but their injection of acid into landscaping plants can cause significant long-term damage. And any populations in your yard could lead to the biting of people or pets if the ants are disturbed. Ant control may also be necessary because a colony can survive for 10 years or longer, with a continually growing population.
Field Ant Identification
Field ants do not have a stinger, but their bite can feel like a sting as they inject formic acid into the break they make in the skin. Some species also inject this formic acid into plants that shade their mounds, killing the plants.
Even when dealing with a single species, field ants can vary greatly in size and color. Field ants are:
- as small as 1/5 inch to as large as 3/8 inch in size.
- red, brown, black, tan, or even two-colored.
- confused with carpenter ants when large in size.
Field Ant Control
If the ants are causing a problem or become a nuisance, the best method of control is direct nest application. As recommended by Clemson University College of Agriculture, Forestry and Life Sciences:
- Completely saturate the ant mound, with a pesticide labeled for mound application of field ants. Complete saturation is necessary because the queen may be living two to three feet below ground, and it is critical that the queen is killed to eliminate the colony.
- If necessary, increase the amount of water so the insecticide completely penetrates the mound.
- Allow a few days for complete elimination, as some of the ants may have been out foraging and not return to the nest for several days.
- If the ants are entering your home, exclusion methods should be implemented, including the sealing or repair of any gaps, cracks or other entry points, including openings where pipes and wires enter the home, door and window frames, and tears or holes in screening.
- A non-repellent insecticide, labeled for this purpose, also can be applied around the perimeter and up and along the foundation wall of the home. Also, treat around doorways and windows, and underneath the siding.
Although it is sometimes stated that water and borax will kill ants, this is not an effective treatment for field ants, according to the University of Wisconsin Extension Service. Rather a liquid insecticide, labeled for this ant and application, containing cyfluthrin, deltamethrin, bifenthrin, carbaryl (Sevin) or permethrin should be used.