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Argentine Ants

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There are about 22,000 species of ants on the Earth. They are found nearly everywhere except in Antarctica, Greenland and a few oceanic islands. There are several organisms that have evolved complicated social organizations; termites, bees, ants and of course human beings. In all of these groups there is a lot of selfless behavior. That is, the individual relinquishes his own needs for the good of the entire group.  
If you have teeny weenie ants in your house forming long lines heading toward your sugar bowl, they are most likely Argentine ants. In the 1890s these diminutive critters, only 1/8 inch long, arrived on a boat bringing sugar and coffee from South America to Louisiana. From this founding group the ants have moved relentlessly across the southern part of the United States all the way to California. Their southern range has been limited by the aggression of fire ants, another introduced species.
In their native region Argentine ants form normal sized colonies. When these colonies meet each other they often fight and they certainly don't cooperate. However, something entirely different has happened in their new promised lands. Here, these ants are so genetically related to one another they have formed mega-colonies. And I do mean mega. The one in coastal California is 560 miles long and ranges from San Diego to San Francisco! The one in the Mediterranean is even larger - over 3,700 miles long. Mind blowing. And they are wreaking havoc on local ecosystems.
In Southern California, Argentine ants have displaced the native ants. Coastal horned lizards thrive on ants. But unfortunately they cannot survive on Argentine ants. Consequently these wonderful charismatic animals are disappearing from the landscape. And that may be only the beginning of the consequences of Argentine ants on the environment.
The Argentine ants now are the largest, most numerous social insects in the world. It obviously pays to cooperate. We should know.

This is Michael Ellis with a Perspective.

Michael Ellis is a naturalist who leads tours throughout the world. He lives in Santa Rosa.


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