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Argentine Ants and Their Control

Close-up of Linepithema humile, commonly known as the Argentine ant, approaching what appears to be a small bit of red candy

There are many species of ants in California, but the one that's the most common and troublesome in Brentwood and throughout the Bay Area is Linepithema humile, commonly known as the Argentine* ant.

Argentine ants are small, usually no longer than one-eighth of an inch in length, and usually are dark brown or black in color. Although first identified and studied in South America, they are now a common and invasive species in most of the world, usually displacing one or more native ant species anywhere they've been introduced.

One secret to the Argentine ant's success is its extraordinary social structure. In most ant species, ants from different colonies will fight each other -- often to the death -- over food and territory. In the case of Argentine ants, however, individual colonies are parts of massive supercolonies whose ranges can span many thousands of square miles, even encompassing entire countries. Ants from separate colonies, but the same supercolony, will not fight; but ants from different supercolonies will.

As it happens, one of the places where two supercolonies of Argentine ants meet happens to be here in California, right around Escondido. When ants from the two supercolonies meet, they fight each other to the death. There's an interesting article and audio program about the situation here. It's pretty fascinating.

Another reason why Argentine ants have been successful all over the world is their adaptability. Although soil dwellers by nature, Argentine ants are content to live in cracks in foundations, under pavement, in leaf litter, and pretty much anyplace else. They're also omnivorous and can happily survive on pretty much anything that's edible.


Ant Control

Close-up of Argentine ants eating a dead fly.

The same factors that have made Argentine ants successful invaders throughout the world also makes them difficult to control.

In addition to being adaptable and non-aggressive toward each other, Argentine ant colonies can be huge and widely dispersed. It's also common to have more than one colony at a location, making it more difficult to directly target and eliminate the nest.

Another thing about Argentine ants that make them difficult to control is that conventional ant sprays may actually make the problem worse. Studies have shown that Argentine ants can increase their reproductive rates to compensate for losses to insecticides; so the use of repellent insecticides can actually increase the population once the ants learn to avoid the treated areas.

That's one reason why it's important not to use do-it-yourself methods to control these ants. Not only are DIY products rarely successful against Argentine ants, but they may make it more difficult for pest control professionals to eradicate the problem.


Bust-A-Bug provides effective, professional control of Argentine ants and other ants in Brentwood, Contra Costa County, and the entire Bay Area. If you're having an ant problem, please contact us for a prompt, professional inspection and consultation. We look forward to hearing from you.


* The common name of Linepithema humile is based on the ant's having first been identified and studied in Argentina. It is now found in most of the world. We apologize for any perceived insensitivity.