Argentine Ants

Argentine Ants: Invasive, Aggressive Ants

Argentine ants are a type of invasive ant species that is native to South America. In the late 19th century, they were accidentally introduced to the United States, where they have since spread to many parts of the country.

Argentine ants are small, measuring just a few millimeters in length, and are usually light to dark brown in color. They are known for their strong, musty smell and their distinctive habit of forming large, interconnected colonies with multiple queens.

One of the most notable characteristics of Argentine ants is their aggressive nature. They are known to invade and displace native ant species, as well as disrupt the natural ecosystem. They are also a common household pest, as they are attracted to sweet foods and will enter homes in search of food and shelter.

If you have an Argentine ant infestation in your home, it is important to take steps to eliminate it as soon as possible. These ants can be difficult to control once they have established a colony and can cause damage to structures and plants.

To prevent an Argentine ant infestation, it is important to keep your home clean and free of crumbs and spills, seal any cracks or openings in your foundation, and remove any sources of standing water around your property. Remember to be vigilant for these invasive pests and to take steps to prevent an infestation in your home. For professional assistance getting rid of Argentine ants, contact us today!

Argentine Ants

The Argentine ant is distributed worldwide. It was probably introduced into the United States in New Orleans in the late 1800s on ships transporting coffee from Brazil, but it is now established throughout much of the United States, including DC, Maryland, and Virginia. Populations of Argentine ants lack colony borders, sometimes extending over entire habitats. The colony has tremendous capacity for growth and expansion due to the numerous queens and splintering off of new colonies. The population of a colony of Argentine ants can reach astronomical proportions.

A colony of Argentine ants typically consists of 10% queens and 90% workers. Unlike other species of ants, virgin Argentine ant queens do not leave the nest on mating flights; instead, they mate within the nest and begin new colonies with a number of workers and males that bud off the parent colony. Males either mate with virgin queens in their own nest or leave on mating flights to find virgin queens to mate with in other nests.

The Argentine ant life cycle consists of four main stages: egg, larva, pupa, and adult. The egg, larval, and pupal stages are hidden within the underground nest and are only seen when nests are disturbed or when workers are carrying them to a different location. The microscopic eggs are white and approximately 0.3 mm long. Although queens lay eggs throughout the year, most of them are laid in spring and summer. The incubation period varies depending on the temperature from 12 to 55 days, with an average of 28 days. The length of time spent in the larval and pupal stages also varies depending on temperature. Following the four larval instars (stages), the larvae molt into pupae, which look like adults except that their legs and antennae are held tightly against the body. The pupae are initially white, but begin to turn darker as they mature. In the final molt, the pupa becomes an adult ant. The time needed to complete the cycle from egg to adult ranges from 33 to 141 days, with an average of 74 days.

Argentine ant workers are 2.2 to 2.8 mm long, and their body varies in color from light to dark brown, with the legs somewhat lighter. Their mandibles are yellowish and dentate (toothed). They cannot sting. The workers emit a musty odor when crushed. Their antennae are 12-segmented, without a club. The queens are brown, 4 to 6 mm long, and recognized by their large size. The queens perform other duties besides laying eggs, such as foraging. The winged males are dark brown and 2.8 to 3.0 mm long.

In winter, Argentine ants often nest out in the open. Small piles of excavated soil may reveal their nest sites. During summer, they move into shade to avoid direct sunlight on the nest. In adverse conditions or the coming of winter, colonies sometimes merge and from super-colonies. With the coming of spring, the super-colony breaks up into smaller colonies that disperse to find new nest sites.

Typically, Argentine ant nests are shallow (8 inches), but in dry soils they can be as deep as 2 feet. In the urban environment of Washington DC, Maryland & Northern Virginia, outside nests are located beneath boards, stones, concrete, and within decaying plant matter and mulch. Nests are often found at the base of plants or trees that are infested with homopterans. Indoors, nests are occasionally found in wall voids, bath traps, and insulation. Homeowners sometimes complain of massive numbers of dead ants found in unexpected places, such as the bath tub.

Many factors influence nest movement and choice of nest sites by Argentine ants. Nest movement may be influenced by nearby food resources, high rainfall, disturbance, seasons, soil temperature, proximity to woody plants, previous site occupation, and higher humidity. Nests are often located in cooler summer sites and warmer winter sites. Nests often coalesce in the winter to reuse nest sites from the last year and increase in number through the spring. The average nests moved 7 to 10 feet, to within 7 to 13 feet of woody plants, which provide honeydew from homopterous insects (like aphids), as well as change soil moisture and temperature. Argentine ants are more concerned with humidity than proximity to food when selecting nest sites.

Argentine ants are very systematic in how they forage. Unlike most ants, which only deposit trailing pheromones on their way back to the nest from a food source, Argentine ants deposit trailing pheromones continuously. This ensures that they will always cover new ground when they are searching for food, and not waste time revisiting the same place. Once they find food, they reinforce the trail in order to recruit more ants to collect the food. Argentine ants are often seen trailing along the edge of a sidewalk or driveway. Trails may consist of thousands of ants traveling to and from their nests.