For your convenience and immediate attention, call 800-381-6331

Field Ants

Facts, Identification & Control

General Facts

Field ants get their name from their penchant for nesting in open fields, though northern species also live in woodlands. The insects also go by the common names of mound ants or thatching ants, which both refer to their preferred forms of shelter. Mounds built by field ants can grow as large as 30 cm in diameter and create an unsightly scene when they occur in the lawns and yards of private residences. Over 100 field ant species live throughout North America.

Appearance / Identification

Field ants are unusually large in size compared to other ant species, ranging from 4 to 9 mm in length. Individual ants display either a solid colour or a combination of black, brown, yellow, and red. Though the insects lack the ability to sting, they are capable of pinching human skin with their mouthparts. Field ants can also expel formic acid from an opening on the tip of the abdomen as a defence mechanism. image of a field ant


While different species of field ants hold different preferences in regard to habitat, none of them invade homes for shelter. Instead, field ants favour outdoor nests. Typically, the insects construct mounds in the soil anywhere in the lawn or yard. Some species prefer to live in more inconspicuous places, such as under firewood piles, bricks, lawn ornaments, trees, rocks, and in lawns.


The primary component of the field ant diet is the honeydew produced by aphids and other plant-sucking insects. However, as field ants are not known to be picky, the pests also feed on sugary substances, soft-bodied insects, seed husks, and dead insects.

Life Cycle / Reproduction

The duration of the field ant life cycle and the specific reproductive processes of the insects tend to vary by species. However, every colony features a queen ant who takes responsibility for laying eggs. The eggs then mature into sterile worker females and male drones. A single field ant colony is capable of surviving a decade.

Problems Caused by Field Ants

As far as pest species go, field ants are relatively tame. Since they do not invade homes, the insects have no effect on food supplies or the structural integrity of buildings. Still, their mounds may prevent the growth of grass or surrounding plants in the yard and can cause problems when the lawn must be mowed. Furthermore, when field ants are disturbed by humans, they pinch the skin and then spray formic acid on the wound which creates a sensation similar to a sting.

Detection / Signs of Infestation

Due to their outdoor nesting behaviour, field ants often remain difficult to spot early on. The appearance of a mound in the dirt around a home is a decent indication of a field ant infestation. Homeowners may also notice adult field ants in the general vicinity. Diligent individuals should check under wood piles, lawn ornaments, and especially large rocks for field ant colonies.

Prevention Tips

The relatively innocuous nature of field ants means that homeowners generally do not need to worry about taking preventative measures against the insects. For those wishing to take action, a few simple habitat modifications can decrease the chances of a field ant infestation. First, locate and fix cracks in the foundation, and repair broken screens on windows and doors to deter any ants from getting inside. Check on drainage to prevent moisture from building up in the soil, and trim shrubs and trees so the branches neither touch nor hang over the home. Finally, keep lawns clear of clutter and debris.

Control / Removal

When a field ant infestation occurs in the yard, the residents of the property may choose to live in peaceful coexistence with the harmless creatures. Once the insects become a serious nuisance, however, homeowners should consider contacting a pest control professional. Often, the application of appropriate pesticides is enough to kill off a colony. Professional pest specialists possess the necessary training, knowledge, and certifications to successfully remove field ants and help prevent further infestation problems.

More Information on Field Ants:
Field Ants in the House
Field Ant Identification
Field Ant Bites
Field Ant Mounds
Field Ants vs. Carpenter Ants