Where Argentine Ants Are Found
You will find Argentine Ants mostly in the southern United States, especially California.
It is generally understood that Argentine Ants may have entered the United States aboard ships carrying coffee or sugar from Argentina during the 1890s. They expanded from the coast throughout California and to the southern parts of the United States.
Argentine Ants find Fire Ants to be fierce competitors, and so Argentine Ant populations are not as numerous in the southeastern parts of the United States.
Since Fire Ants and other competitors are largely absent in California, this state has seen the Argentine Ant thrive in the temperate and damp coastal regions. Argentine Ants have killed and displaced native Ants, many of which are ten times larger in size.
You probably won't ever see a winged form of the Argentine Ant, because mating is usually accomplished in the nest, not in mating flights. Argentine Ants are aggressive, often eliminating other types of Ants in the same area. They also destroy and eat other household pests such as cockroaches and exposed termites.
However, they prefer sweet foods and are often found tending aphids or scale insects on plants, using them as a source of honeydew.
Their usual habitation is outside, but these Ants can present a problem when they come inside foraging for food. They rarely nest in walls of buildings, as some other Ants commonly do. They enter to forage and then exit, returning to the nest.
The wingless worker Ant (most commonly spotted), is light to dark brown, about 1/12–1/8-inch long. The antennae are strongly elbowed (12 segments) and there is a single node in front of the abdomen (the waist). Queens are 1/6–1/4-inch long.
Here are some things to look for when identifying Argentine Ants:
- Uniformly dull brown color
- Petiole (the node that separates the thorax from the abdomen) has one erect node
- Thorax (middle part supporting the legs) is uneven in shape when viewed from the side
- Musty odor emitted when Ant is crushed
Photo and ID text courtesy of UC IPM Online
The winged queens can produce fertile eggs for up to 10 years after mating once with a winged male. Another difference in this type of Ant compared to other Ants, is that several productive queens can share the same colony.
One or more of these productive queens may leave with some of the workers to form a new colony when it gets crowded (this is known as budding).
The grub-like larvae are fed and tended by the workers, pupate, and then emerge to join their sisters in the colony (worker Ants are all sterile females). The white eggs are laid in the summer, and the larvae emerge after about 28 days.
The larval stage may take from 11–60 days. The pupal period may last from 10–25 days or more. Development from egg to adult usually takes about two months, but may take up to 4–5 months.
During the summer months, highly mobile satellite nests are usually established close to food sources.
Argentine Ants can persist in conditions where other Ant species could not survive.
They like to nest in moist soil next to buildings or under them. They can be found near sidewalks or plants. They nest near water and food sources.
Foraging Ants will enter the house when outside conditions are extremely dry or wet.
Colonies are large, often containing hundreds of queens. The queens and larvae eat protein/grease foods (and baits) almost exclusively, while the workers eat sugar-based foods (and baits).
They are extremely mobile and will relocate colonies frequently. Argentine Ants can be easily tracked because they generate strong pheromone trails when foraging. In many areas, you will see pheromone trail super-highways three and four lanes wide.
Argentine Ant workers prefer sweet foods such as syrup, fruit juices or plant secretions, but will gather protein/grease-based foods to bring back to the queens and larvae. They gather food day and night. Of all the smaller sized Ants, this one prefers sweet more than protein.