All About Argentine Ants

If you find small, brown ants in your home and live in the Southeastern United States, there is a good chance it is Argentine ants. The Argentine ant is an invasive species that is spreading throughout the United States. Introduced to the United States about 100 years ago, they are most commonly found in California and the Southeastern United States. The Argentine ant, whose scientific name is Linephithema humile, is light brown in color and normally about 3/16 inch in length. They feed on honeydew, which is produced by aphids and scale insects.

What makes Argentine ants unique is that they don’t fight ants within their own colony. This makes it possible for colonies to form into massive super colonies, which stretch for miles. Super colonies can include a million workers with several hundred queens. There are known super colonies on the Mediterranean coastline and in California, with one in progress in North Carolina.

There are a couple factors that can drive Argentine ants to your home. The first thing to consider is your yard. Argentine ants are attracted to mulch, leaves, branches, and other yard debris. In addition, if you have shrubs or trees near your home, it can be problematic. In their search for honeydew, they often often crawl on plants. Thus, if your plants are touching your home, it provides easy access.

The weather will also affect the likelihood of a home invasion. During the winter, the ants will look for a protected area from the cold, such as inside your home. During the spring and summer, ants will move back into their outdoor nests. Warm weather also promotes growth and will often increase the ant population. If the weather is dry, it will drive ants into your home looking for water. This means it’s important to prevent standing water or puddles within your home.

While Argentine ants don’t harm humans, they are difficult to get rid of once they enter a home. Moreover, Argentine ants wipe out other species of ants, making them problematic for local ecosystems. For instance, when Argentine ants knock out a local ant species, other animals such as lizards, or birds may not have enough food. At the other end of the spectrum, the ants might plant seeds, which is also important for the balance of the ecosystem.

Unfortunately, getting rid of Argentine ants can be complicated. Because their colonies are spread out over miles, there isn’t one nest to treat making chemical sprays difficult. Baiting is another method for treatment but it can be challenging to find a bait that ants are attracted to. Luckily, researchers at University of California- Riverside have found a potentially more effective treatment. They added pheromones to the bait, which reduced ant activity by 74%. Bait without pheromones only reduced activity by 42%.

Since Argentine ants can be challenging to treat, it’s a good idea to try to prevent them. By minimizing food and water in your home, especially in difficult to see areas, such as crawl spaces, you can make it less likely for ants to enter. Plus, keeping your yard free of debris will help prevent them from forming nests nearby.

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Spicer, Eleanor. “NATURALIST'S NOTEBOOK: Coastal Invasion: The Argentine Ant : Coastwatch.” Coastwatch, NC State University , issues/2009-2/holiday-2009/naturalists-notebook-coastal-invasion-the-argentine-ant/.
University of California - Riverside. "New method to stop Argentine ants: Researchers add Argentine ant pheromone to bait and find 74 percent reduction in ant activity." ScienceDaily. ScienceDaily, 1 March 2016. .
Suiter, Daniel R., and Brian T. Forschler. “Urban Entomology Pest Series .” Mar. 2011.