It sounds like a horror movie: Biting ants invade by the millions. A camper's metal walls bulge from the pressure of ants nesting behind them. A circle of poison stops them for only a day, and then a fresh horde shows up, bringing babies. Stand in the yard, and in seconds ants cover your shoes.
It's an extreme example of what can happen when the ants -- which also can disable huge industrial plants -- go unchecked. Controlling them can cost thousands of dollars. But the story is real, told by someone who's been studying ants for a decade.
"Months later, I could close my eyes and see them moving," said Joe MacGown, who curates the ant, mosquito and scarab collections at the Mississippi State Entomological Museum at Mississippi State University.
He's been back to check on the hairy crazy ants. They're still around. The occupant isn't.
The flea-sized critters are called crazy because each forager scrambles randomly at a speed that your average picnic ant, marching one by one, reaches only in video fast-forward. They're called hairy because of fuzz that, to the naked eye, makes their abdomens look less glossy than those of their slower, bigger cousins.
And they're on the move in Florida, Texas, Mississippi and Louisiana. In Texas, they've invaded homes and industrial complexes, urban areas and rural areas. They travel in cargo containers, hay bales, potted plants, motorcycles and moving vans. They overwhelm beehives -- one Texas beekeeper was losing 100 a year in 2009. They short out industrial equipment.
If one gets electrocuted, its death releases a chemical cue to attack a threat to the colony, said Roger Gold, an entomology professor at Texas A&M.
"The other ants rush in. Before long, you have a ball of ants," he said.
A computer system controlling pipeline valves shorted out twice in about 35 days, but monthly treatments there now keep the bugs at bay, said exterminator Tom Rasberry, who found the first Texas specimens of the species in the Houston area in 2002.
"We're kind of going for overkill on that particular site because so much is at stake," he said. "If that shuts down, they could literally shut down an entire chemical plant that costs millions of dollars."
And, compared to other ants, these need overkill. For instance, Gold said, if 100,000 are killed by pesticides, millions more will follow.
"I did a test site with a product early on and applied the product to a half-acre ... In 30 days I had two inches of dead ants covering the entire half-acre," Rasberry said. "It looked like the top of the dead ants was just total movement from all the live ants on top of the dead ants."
But the Mississippi story is an exception, Rasberry said. Control is expensive, ranging from $275 to thousands of dollars a year for the 1,000 homes he's treated in the past month. Still, he's never seen the ants force someone out of their home, he said.
The ants don't dig out anthills and prefer to nest in sheltered, moist spots. In MacGown's extreme example in Waveland, Miss., the house was out in woods with many fallen trees and piles of debris. They will eat just about anything -- plant or animal.
The ants are probably native to South America, MacGown said. But they were recorded in the Caribbean by the late 19th century, said Jeff Keularts, an extension associate professor at the University of the Virgin Islands. That's how they got the nickname "Caribbean crazy ants." They've also become known as Rasberry crazy ants, after the exterminator.
Now they're making their way through parts of the Southeast. Florida had the ants in about five counties in 2000 but today is up to 20, MacGown said. Nine years after first being spotted in Texas, that state now has them in 18 counties. So far, they have been found in two counties in Mississippi and at least one Louisiana parish.
Texas has temporarily approved two chemicals in its effort to control the ants, and other states are looking at ways to curb their spread.
Controlling them can be tricky. Rasberry said he's worked jobs where other exterminators had already tried and failed. Gold said some infestations have been traced to hay bales hauled from one place to another for livestock left without grass by the drought that has plagued Texas.
MacGown said he hopes their numbers are curbed in Louisiana and Mississippi before it's too late.
The hairy crazy ants do wipe out one pest -- fire ants -- but that's cold comfort.
"I prefer fire ants to these," MacGown said. "I can avoid a fire ant colony."