Invasive Crazy Ants Are Eating Up Invasive Fire Ants in the South

How ecosystems will function if fire ants suddenly disappear and are replaced by crazy ants remains an open but worrying question

A crazy ant queen.
A crazy ant queen. Joe MacGown, Mississippi Entomological Museum

Since fire ants first invaded the U.S. through cargo ships docking in Mobile, Alabama, the aggressive pest has taken a firm hold in the South and Southwest. More than $5 billion is spent each year on medical treatment and fire ant control, according to Food and Drug Administration, and the ants cost an additional $750 million in agricultural damage.

Now, however, there’s a new ant on the block. The crazy ant – also an invader from South America – is displacing fire ants in the U.S. by gobbling them up. But this unprescribed cure is likely worse than the disease it’s treating. The Los Angeles Times reports:

Like fire ants, these South American invaders seem to be fond of electrical equipment. But unlike their stinging red counterparts, the tawny crazy ants create mega-colonies, sometimes in homes, and push out local populations of ants and arthropods.

Thus far, the crazy ants are not falling for the traditional poisons used to eliminate fire ant mounds. And when local mounds are destroyed manually, they are quickly regenerated.

Though the crazy ants don’t deliver the same burning bite as fire ants, they do stubbornly make their nests in bathroom plumbing or in walls. So far, researchers haven’t documented any native animals preying on the crazy ants, so their colonies are allowed to run amok, sometimes growing 100 times the size of other species of ants living in the area.

This isn’t the first time one ant invader has been displaced by another. The Argentine ant arrived back in 1891, followed by the black ant in 1918. But the fire ant put an end to those two invasive species when it arrived a couple decades later. Now, the fire ant’s own day of invasive reckoning may have arrived, but rather than feel relieved, researches are worried. Southern ecosystems have had time to adjust to fire ants. Crazy ants—well, who knows what they’ll do?

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