Pavement Ant

The pavement ant is a small, hardy species originally native to Europe that has become widespread across North America since its introduction in the 1700s and 1800s. True to its name, it commonly nests beneath pavement, sidewalks, and building slabs, often revealing its presence through small mounds of excavated soil pushed up through cracks.

Colonies are territorial, and neighboring pavement ant colonies frequently clash in large-scale skirmishes along shared boundaries, with hundreds of workers grappling in visible masses on sidewalks, particularly in spring when colonies are re-establishing territory after winter dormancy.

The species has been recently reclassified taxonomically; populations long called Tetramorium caespitum in North America are now recognized as the related species Tetramorium immigrans.

• Small, robust workers about 2.5-4 mm long, reddish-brown to blackish
• Head and thorax marked with fine parallel grooves (striations)
• Two nodes on the petiole, distinguishing it from single-node species like odorous house ants
• A pair of small spines at the rear of the thorax
• Possesses a functional stinger
• Small mounds of loose soil often visible at pavement cracks near nest entrances

Pavement ants are common throughout the northern and eastern United States, southern Canada, and much of Europe. As the name suggests, they favor nesting beneath pavement, sidewalk slabs, driveways, and building foundations, though they also nest in open soil, under stones, and within mulch beds in and around gardens and lawns.

These ants are omnivorous scavengers, feeding on insects, seeds, and a wide variety of household and garden food sources, and they also tend honeydew-producing insects. They are notably territorial, and in spring, large numbers of workers from adjacent colonies often engage in extended battles along boundary lines, a visible and well-documented behavior sometimes called "ant wars." Foraging workers travel along scent trails to food sources both outdoors and, occasionally, indoors.

Pavement ants undergo complete metamorphosis from egg to larva to pupa to adult. Colonies typically contain a single queen, though multiple-queen colonies occur, and populations can reach several thousand workers. Winged reproductives are produced seasonally and undertake mating flights, usually in summer, after which newly mated queens seek a nesting site to found a new colony.