[Pest Profile] Argentine Ant

Description

These ants lack spines on the thorax, which is unevenly rounded when viewed from the side, have a single node on the petiole, and do not have a circle of hairs at the tip of the abdomen. The eyes are located close to the base of the antennae and appear to be looking forward. Males are slightly smaller and a shiny brown-black.

Biology

Colonies consist of several hundred to several thousand workers and several queens. They are located in moist areas near a food source. Swarmers are rarely seen because mating occurs inside the nest.

Habits

Overwintering nests are large, may have several queens, and are found deep in the soil and in buildings near heat sources. In the spring, these nests disperse with smaller colonies developing in moist soil, in trees, and under stones and concrete slabs. The colonies are mobile, relocating to more acceptable nesting locations whenever necessary. Ant numbers decrease somewhat during this period. They attack, destroy, and eat other household pests, such as cockroaches.

Control

Outdoors, look for Argentine ants trailing up next to the foundation, sidewalks and driveways just below the grass line. All cracks and gaps in exterior walls should be sealed. All debris from the exterior of the structure and other items on the ground where these ants nest should be removed. Control is often difficult because the colonies are dispersed.

Workers are good at finding sweets in homes and in establishing trails, which can be used to find the nests. They are attracted to and feed on sweet- and protein-based baits. Baits should be placed where ant trails have been established. Unless using containerized baits indoors, baits should be placed so they are inaccessible to children and pets. Baits should be checked frequently for activity. Exterior nests should be drenched with a liquid formulation. When the nests can not be located, a barrier spray using a microencapsulated or wettable powder formulation should be applied to foundations, plants and soil immediately adjacent to the building.

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•Found throughout the southern United States and California

•Argentine ant workers are 1/16-inch long and light to dark brown

•Queens are 1/8- to 1/4-inch long, brown, and covered with fine hair

•Developmental time (egg to adult) is 33-141 days and averages 74 days

•Argentine ants typically live in nests outdoors near a food source but become major pests when they forage indoors for food

•They are very aggressive and eliminate other ant species in the area they colonize

•Argentine ants prefer sweets