Argentine Ant Colony

Argentine ants (Linepithema humile) were introduced into the United States from South America around 1880, and like most other invasive species, they have become an agricultural and urban pest problem. The Argentine ant can be found in the southern United States from North Carolina to Florida and west through the gulf states and throughout much of coastal California. Freezing temperatures and lack of water are the limiting factors to the success of this ant species.

While Argentine ants are omnivores who will eat almost anything of plant or animal origin, they prefer sweets and will feed on honeydew and plant nectar. In addition, they may also scavenge on dead insects. Inside homes, they will eat sweet and greasy substances and may infest food products.

Argentine ants nest in many different habitats. Outdoors, nests are usually associated with moist, protected locations such as in the soil under rocks, refuse piles, mulch, concrete slabs, wood debris and fallen or dead logs. Inside a home, Argentine ants may make nests in the walls of bathrooms and kitchens, in crawl spaces beneath the floor and around places where moisture from water leaks is allowed to accumulate.

Outdoors, a colony of Argentine ants likely consists of many different nest sites that are connected by ant trails that can connect various nests. These ants live together cooperatively and express little, if any aggression and competition towards each other. In addition, colonies will coexist with other colonies resulting in the ants work together to form Argentine ant “super colonies.”

Reproduction and mating within Argentine ant colonies is quite different than other ant species. Winged queens mate once with a winged male, after which the queen can continuously produce fertile eggs for as long as 10 years or until her death. Unlike most other ants, several productive queens can share the same colony. When colonies become too crowded, one or more queens will leave with some workers to form a new colony in another location (a process called budding). Budding usually occurs in the spring and summer.

For ant colonies with only one queen, when that queen dies the entire colony dies because no more ants are being produced. However, for multi-queen colonies such as the Argentine ants, another queen simply moves into the nest and takes over the role of laying eggs formerly carried out by the deceased queen. In addition, Argentine ant reproductive winged males and females do not leave the nest in a swarm, unlike other ant species. Instead, they mate within the nest, a behavior that is important since it reduces exposure of the reproductive to predators such as birds and other small animals.

Since the Argentine ant colonies are so large and their habitat so diverse, well established nests and colonies are not likely to be totally eliminated from either outside or inside the home. If Argentine ants are a problem, contact your pest management professional who will use his expertise and knowledge to plan and execute an integrated pest management program. The key components of an Argentine ant control program are habitat removal, moisture removal, food source removal, sanitation and treating both inside and outside with insecticide baits.