Argentine Ants Invade!

Native to northern Argentina, Uruguay, Paraguay, and Southern Brazil, the Argentine ant, also called Linepithema humile, are an extremely invasive ant species.  Homeowners across the California coast are familiar with the Argentine ant as this is the most common species that invades California homes. How can you tell if an ant is an Argentine ant? The Argentine ant is brownish red in color.  Queen Argentine Ants can be up to ½ an inch long, and they even help worker ants gather food.  Their workers are closer to 1/8 of an inch long. Argentine ants have less hair than typical ants and they have an uneven thorax (the middle portion of the ant) and a raised abdomen (the back portion of the ant).  They are often found marching in long lines towards food.

Why are these little guys invading your home? Argentine ants prefer eating sweets, but they are not too picky.  These ants will eat almost anything, including meats, eggs, oils and fats.  Argentine ants’ abilities to find food is uncanny, so when you set a piece of fruit out in your kitchen, think again as you might find that fruit an object of the ant’s desire.

Where did this swarm of insects come from? Originating in the forests of northern Argentina, these ants caught a ride to the west coast of the United States as a result of global commerce. A unique behavior of the Argeintine ant is the formation of “supercolonies”. A supercolony occurs when many colonies band together and act as one unit, despite the presence of many queens. Argentine ants are a problem in southern California because of the presence of a supercolony that stretches along the coast as far as northern Los Angeles county all the way to the Mexican border.  The other two “supercolonies” cover the Ishikari coast of Japan, and 4,000 miles of the Southern European coast.  Japan’s “supercolony” is the largest, containing over 300 million workers, 1 million queens, and 45,000 nests.  In 2009 it was discovered that these three colonies are actually all a part of one global “megacolony.”  This is a phenomenon where worker ants of one species work together with worker ants of the same species but from other nests.