Northern Plains Integrated Pest Management GuideIPM

Authors: Ashley Mueller, Buyung Hadi

Ants are one of the most common pests that can be found in and around homes. Ants are social insects, and they live together in colonies. They are divided into three classes called castes: queens, males, and workers. Each caste serves the colony in specific way. Queens lay eggs and care for the brood; males play a vital role in reproduction; and workers provide food to the colony by foraging. Ants use pheromones to create invisible odor trails. The workers follow the odor trails to and from the nest while foraging for food. Indoors, ants are often seen following trails.

Although ants can be a nuisance, they can also contaminate food, wreak havoc on yards, and cause structural damage to buildings. There are many ways homeowners can prevent ants from coming indoors. Identifying problematic ants is essential in determining how an infestation is managed.

Identification

Adult worker

Pavement ant workers are about 1/6 inch long, and they are dark brown to black in color. They often excavate underground nests on the pavement cracks with recognizable soil piles on the pavement. Pavement ants are found in the eastern half of the U.S., and they are especially prevalent in the upper Midwest.

Habitat

In addition to nesting on pavement cracks, pavement ant colonies can be found under objects lying on the ground, like stones, logs, concrete slabs, and mulch in landscaped beds. It is rare for pavement ant colonies to be found indoors, but in such cases, they can be found in walls and attic insulation and along the foundation.

Life Cycle and Seasonal History

Pavement ant colonies are large, with usually one functional queen. Reproductive pavement ants typically swarm in late spring and early summer. After the ants mate, the queens burrow into the soil, where they lay eggs. In a two-to-three month period, a colony’s first workers have developed. Colonies without queens have been known to occur.

During the winter, pavement ants may nest inside structures, close to a heat source. Winged reproductive ants may emerge during any season in heated structures.

Human Interaction and Urban Impact

Pavements ants are not medically or economically important pests. Although pavement ants have a stinger, they are rarely aggressive against humans. Any medical questions or concerns related to a pavement ant sting should be directed towards a physician.

Magnolia scales being tended by ants

Pavement ants are a common house and building invader, often going indoors foraging for food. Foraging typically occurs at night. Vegetable gardens may be at risk of damage by foraging pavement ants. Although a nuisance, pavement ants rarely cause significant damage.

Persons raising poultry may be especially concerned about the presence of pavement ants since they are a known intermediate host of two poultry tapeworms.

Prevention and Management Approaches

Pavement ants feed on dead insects, sweets, grease, and pet food . Foods should be kept in tightly sealed containers. Sites of food preparation should be kept clean and free of grease. Trash cans into which food is dumped should be taken out on a regular basis. Potential openings into the house or building, such as a windowsill or under a door, should be sealed to prevent ant entry.

If an ant trail is observed indoors, the ants can be managed until a long-term solution can be implemented. If ants are going to a food source, it is recommended that the food source not be removed until after the ants are killed. Wiping a sponge dipped in soapy water over the ant trail kills the ants, and it is effective in removing pheromones. If the source of the ants is located, silica gel/pyrethrum can be applied in a small amount in the hole or crack. Boric acid or an inorganic desiccating dust may be used for residual control. Boric acid baits are available in sweets and protein food bases, making them attractive to pavement ants.

Outdoor nests can be controlled using insecticidal baits. Baits are picked up by workers, and they are distributed to colony members. Most baits are slow acting, and it may take two weeks or longer to control the population. Baits should be placed where ant activity has been observed, making certain that children and pets cannot reach them. Always use precaution and follow the label carefully before using any insecticide. Insecticides have a certain amount of toxicity to mammals; children and pets are especially at risk.