Allegheny Mound Ants

Facts, Identification & Control

Latin Name

Formica exsectoides


What do they look like?

allegheny ant illustration
  • Color: Allegheny mound ants have a reddish head and thorax. The abdomen and legs are dark brown to black.
  • Size: The workers vary in size from 3.2 to 6.3 mm.

They do not sting, but they can bite if the mound is disturbed.

How Did I Get Allegheny Ants?

Allegheny ants nest in open areas with plenty of sunshine and construct large mounds made from soil particles they excavate from underground tunnels and bring to the soil surface. Residents with ant mounds in their yards may see the insects crawling inside by accident. Otherwise, these pests rarely enter homes. They feed on other insects and have little or no interest in human food and rarely enter buildings unless acceptable prey insects are located inside.

How Serious Are Allegheny Ants?

Allegheny ant mounds need warmth to survive and practice a very interesting behavior to keep the colony in direct sunlight. Allegheny ants reduce the amount of shade created by plants by stinging and injecting formic acid into nearby plants and trees to strip away all vegetation within 50 feet of the mound. Multiple colonies destroy landscaping and are hard to remove. The ants will bite if threatened.

How Do I Get Rid of Allegheny Ants?

What Orkin Does
If Allegheny mound ants are nesting on a property, it is usually best to call a pest control professional. There are several methods they can use to control Allegheny mound ants.

The Orkin Man™ is trained to help manage Allegheny Ants and similar pests. Since every building or home is different, your Orkin technician will design a unique program for your situation.

Keeping ants out of homes and buildings is an ongoing process, not a one-time treatment. Orkin’s exclusive A.I.M. solution is a continuing cycle of three critical steps — Assess, Implement and Monitor.

The Orkin Man™ can provide the right solution to keep ants in their place…out of your home, or business.

For more information or to schedule an inspection, please contact your local Orkin branch office.

Signs of Allegheny Mound Ant Infestation

The most visible sign of Allegheny mound ants is the mound, hence their name. Few other ants in the U.S. build as visible a mound. Other signs would be the workers as they forage for food.

Behavior, Diet & Habits

The workers make galleries and tunnels in the ground. The tunnels extend as deep as almost 1 m (~3 ft) into the soil. As they dig, the workers pile the excavated soil up to make the mound. The mounds can reach records of about 5 m (~16ft)  in diameter, especially with older nests found in fields and wooded areas. The mounds that these ants build are frequently mistaken for fire ant mounds.

Allegheny mound ants nest in fields, pastures and wooded areas. They also live in playgrounds and residential lawns in rural and suburban areas. They do not usually enter homes, but workers often forage on patios and decks.

Allegheny mound ants eat insects and honeydew, a sweet substance produced by sap-feeding insects like aphids or scales. The workers protect aphids and other insects that produce honeydew. The ant workers sometimes damage trees and shrubs by chewing openings in the bark and spraying formic acid. This is done to kill trees that are shading the nests. If these ants are disturbed, they give off a distinct formic acid odor.


Queens produce eggs that become workers and reproductives. To establish a new colony, a mated queen and a contingent of workers leave the colony to select a new nesting site.

More Information

The Allegheny mound ant is a type of mound-building ant in the United States. These ants are found along the Atlantic coast from Nova Scotia to Georgia. They are most common in the Midwest and Northeast.