Tawny crazy ants, named for their color and their "herky-jerky" pattern of foraging, first showed up near Houston in 2002.
Hailing from northern Argentina and southern Brazil, they seek out cavities to nest in, like walls, basements -- or air conditioning units.
Less than 1/8 inch long, their small size allows them to crawl inside cellphones, computers and appliances, where protected cavities are "just great" for them, Edward LeBrun, a researcher at the University of Texas, told LiveScience.
Reproducing in large numbers, sometimes outnumbering local species of ants 100-to-1, they've developed a preference for swarming into electronics devices like air conditioners and farm equipment like pumps, experts said.
In one case, the ants quickly spread to 90 out of 150 air-conditioning units in an apartment building in Waco, Texas, said Mike Matthews, who works for Austin-area pest control business The Bug Master.
"When you open these things up, you see thousands of the ants, just completely filling them up," he said.
That infestation took about two months to control, he said.