Invasive species watch: crazy ants

It doesn't take long to realize how the invasive crazy ant got its unusual name. While most ant species march in disciplined lines, crazy ants (Paratrechina sp. nr. Pubens) spread across the ground haphazardly, like miniature sailors spilling into port after months at sea.

Odder still, crazy ants are inexplicably attracted to electronics. Swarms of ants can even short out electrical boxes by chewing through soft insulation and exposing “hot” wires. Also known as ‘Rasberry’ ants after Tom Rasberry, a Houston exterminator who first identified the species in Texas, crazy ants have been spotted throughout the United States, and are a particular nuisance throughout the Gulf Coast region.

Crazy ants may not pack the punch of fire ants, but they’re capable of creating costly damage and pose a clear threat to native wildlife. They are indiscriminate eaters and will swarm and consume everything from seeds and plants to bird eggs to beehives. Anecdotal reports from the Houston area tell of small woodlands devoid of all wildlife following crazy ant infestations. In fact, the only thing crazy ants don’t seem to eat is bait—colony-killing poisons have yet to prove effective.  

Now, seven years after the species was first sighted in Houston, crazy ants have spread west and have made their way to San Antonio. According to Jim Bergan, director of science and stewardship for The Nature Conservancy of Texas, this is nothing less than a call to action.

“The damage crazy ants have caused to wildlife and property has just begun to be documented, but the early data tells an alarming story” he said. “Rolling back the clock and eradicating the billions of ants found in a major city like Houston is extremely difficult and expensive. But here in San Antonio, we have the chance to stop the spread before it really starts. Stopping crazy ants requires the vigilance and participation of all Texas landowners and business owners that encounter them.”

Crazy ants are smallish—no larger than 3 mm—and reddish brown in color. They’re prone to colonizing near urban or commercial areas.

To report crazy ants in your area, contact your local Texas county extension office. 

To learn more about our work, including other invasive species we help control, visit nature.org/texas.