Pest Library

Characteristics

Workers are small and similar in size with only about one-twelfth of an inch long.

Other characteristics:
• Uniform brown color
• Single upright node found between the thorax and abdomen
• Workers that are disturbed or crushed emit a stale, musty odor
• They do not sting, but they bite

Habitat

The Argentine ants are common in Northern Argentina, but is now widely distributed in urban, natural and agricultural habitats in the United States. They are known as pests because they are capable of instigating changes in the ecosystem, such as the extinction of native arthropods, and disruption of native ants, pollinators, and vertebrates.

In homes, these ants have the ability to spread rapidly. A contributing factor to this is the availability of water that is common in urban areas. These ants become a nuisance insect by penetrating landscapes that feature favorable microclimates like potted plants and walkway stones and bricks. They can enter homes through cracks and other spaces. They will search for food and water, and can establish large colonies in homes.

Nest sites:
• Rotting wood
• Trees
• In moist leaf litter
• Bricks or boards
• Refuse piles
• Under bark
• Under house siding
• In wall voids
• Under carpeting
• Behind brick veneer
• In potted plants
• Bathrooms and kitchens
• Garbage piles

Behavior

These ants are prolific breeders and are constantly moving. A single colony can contain 10,000 workers, hundreds of reproductive queens, and hundred more colonies that are hidden from view. They can easily reach a million if there are hundreds of undiscovered colonies surrounding a home.

Argentine ants are very aggressive and can overtake other ant species, even those ants that are much larger and have a more powerful sting than they. Although they are aggressive toward other ant species, they can peacefully coexist with other Argentine ant colonies. They can even cooperate with them so that they can create “super colonies.”

Food

Argentine ants love sweets and proteins, and can consume a variety of different foods, such as syrups, eggs, juices, tuna, dead spiders, vomit, feces, rodents, and any other organic material they can get. They are great scavengers and can enter homes during hot, dry weather for food and water. They collect honeydew and feed on extrafloral and floral nectarines.

They provide plant pest insects, such as mealybugs, scales, and aphids protection to get sweet honeydew secretions as payment for their tending. They can also make other pests to move to better food sources so they can better get honeydew production, which leads to greater plant damage and higher pest densities.

Life Cycle

During mid-winter, no reproductive activities and minimal birthing occur. However, eggs are still produced during late-winter, and will have sexual forms by May. Once the females emerge, mating happens. Male production is normally controlled by the food that is available to the larvae. From mid-March until October, worker production increases. But, their numbers will drop during the winter months, thus the cycle of their reproduction occur. Their colonies can easily be created by a single queen and a few workers.

Although there is a period where the worker production decreases, but they still possess a threat to the area where they have their nests. A worker ant may just live for a month or two, however, their queens can live up to ten years, especially if the conditions are favorable. And, even when their queen dies, their colony can still survive because another queen can simply take her place and take over the role of the reproduction.

Other Information and Tips

It is impractical to spray pesticides to these ants, although you may be able to kill hundreds of them. However, if you are not able to find the queen, you will still find them going inside and outside your home searching for food and water again. An effective way to control Argentine ants is by the use of slow-acting poison bait that they can carry back to the nest site. Such bait can eventually kill the ants inside the colony and the queens. Although this may take some, but it can completely eradicate a colony, especially if the baiting is done right.

Photo: Linepithema humile (Argentine Ant) by S. Rae, used under CC BY 2.0 / resized from original