Formica Ants Invade Properties Where They Nest Beneath Turf Grass, Within Structural Foundations, Beneath Concrete Slabs, Rotting Structural Wood, And Sometimes, Wall Voids

Several ants belonging to the Formica genus become destructive pests when they establish nests on residential lawns and structures. These ants are commonly referred to as “field ants,” but they go by many other names that reflect their preference for nesting outdoors, including “thatching ants,” “red ants” and “wood ants.” These names are commonly applied to any Formica ant species that exhibits pest behavior. However, to be accurate, there are two groups of Formica ants that become pests when they establish nests on properties. One group, field ants, live in colonies that are located beneath turf grass and the base of plants, making them hard to locate. The other group, thatching (wood) ants, build conspicuous nests as large as 10 feet in diameter and 5 feet in height, resulting in serious damage to turf grass, ornamental plants, and in some cases, structural foundations.

Thatching and field ants are among the most commonly encountered ant pests within residential yards, and workers sometimes invade homes in large numbers during the spring, while their frightening swarms are often witnessed around homes during the fall. During the winter, thatching ants expand their nests to reach 4 feet below the ground surface where temperatures are sufficiently warm. One single queen initiates a new colony, but colonies continue to grow in size and population for a period of 20 years, and during this time, several queens can become established within one colony nest. Although these ants swarm in order to colonize new areas, surplus queens can simply leave an existing colony in order to start a new one nearby. Both thatching and field ants closely resemble carpenter ants due to their comparable body sizes, which can exceed 10 mm. Also like carpenter ants, thatching ants may tunnel through rotting structural wood, and while many experts insist that Formica ants do not nest in homes, workers may establish secondary nests within cracks and crevices on a home’s exterior walls, and eventually, within interior wall voids.

Have you ever found large ant mounds on your lawn grass?