Several Houston-area suburbs can attest to crazy ants’ destructive habits: swarming across the landscape, nesting in virtually every cavity they can find, along the way ravaging electronics, taking up residence in drywall and disrupting local ecosystems.

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AUSTIN, Texas — Hoping to illustrate his point about a new pestilence that has arrived in Central Texas, ant researcher Edward LeBrun pointed to a Mason jar in his office.

The jar looked like it was filled with blackberry jam. But it was filled, top to bottom, with ants, roughly 181,000 of them. More specifically, tawny crazy ants, a bug causing such a problem that it has supplanted the fire ant atop the list of pests that researchers say Texas needs to get under control.

Several Houston-area suburbs can attest to crazy ants’ destructive habits: swarming across the landscape, nesting in virtually every cavity they can find, along the way ravaging electronics, taking up residence in drywall and disrupting local ecosystems.

Crazy ants have become one of the main topics of study at the Brackenridge Field Laboratory, a University of Texas facility in Austin where LeBrun works. His point with the jar full of crazy ants: All the researchers had to do was leave nine 50-milliliter tubes on the ground in an area infested with crazy ants, and collect them a day later. The ants swarm in such vast numbers that the researchers didn’t even have to bait the tubes.

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“An invasion of these can be so extreme,” LeBrun said, “that it’s hard to call it just a nuisance.”

In Pearland, outside Houston, where crazy ants were first spotted in 2002, some people talk wistfully of fire ants. Exterminator Mike Foshee found them around the time his air conditioner stopped working. He fired up the Shop-Vac to clear the vents in his living-room floor and, by the time he had finished, he had sucked out five gallons of ants.

They got inside the television, making the picture go catawampus, and streamed frantically across the kitchen floor. He poisoned them, only to see them come streaming back. The subdivision remains overwhelmed by crazy ants.

“When you talk to people who live in the invaded areas, they tell you they want their fire ants back,” LeBrun said.

Crazy ants have spread to 23 Texas counties, including Travis, Hays and Williamson, according to Texas A&M’s Center for Urban and Structural Entomology.

Crazy-ant populations expand slowly, perhaps a couple of hundred yards a year. It’s humans who appear to be spreading them across vast distances, LeBrun said, first by bringing them up from South America, and then letting colonies sneak into potted plants or plywood or hay bales and hitch a ride.

Hard to kill or drive out

Crazy ants and fire ants are natural rivals in parts of Brazil and Argentina, and both probably came to the southeastern United States as stowaways on ships. Invasive fire ants arrived in the 1930s and spread at an alarming rate across the South, in part because their venom is so potent that most biological rivals have no chance.

Crazy-ant venom is far less toxic, and their bite at most causes “a minute of pain that quickly fades,” according to A&M’s experts. But crazy ants can wipe out fire ants. Researchers at UT found crazy ants do this by smearing themselves in a secretion that neutralizes fire-ant venom, essentially rendering them invulnerable to it.

No other Texas ants appear adapted to take on crazy ants, either. They drive out almost all other bugs, including spiders, through sheer weight of numbers, LeBrun said. Even nesting songbirds can be overrun by crazy ants, A&M experts say.

Crazy ants are also remarkably difficult to drive out. When hurt, they emit a pheromone that, like a battlefield radio, calls in nearby reinforcements. This means the ants will swarm into electrical sockets in which their cousins were just fried, or march across yards that pesticides had just turned into a crazy-ant killing field. LeBrun said such efforts often just create “a tiny little gap in an ocean of ants.”

Nature has a way of keeping crazy ants in check in South America, though. Several other species of ants tend to kill crazy ants by outcompeting them for food.

The big problem in Texas is that no local species appears to beat crazy ants. Bringing in the South American ants would only create another problem, LeBrun said, because many of the ants in that habitat could turn out to be highly invasive.

So what can beat them?

Nature might provide relief for the rest of the country. Crazy ants are subtropical and, though researchers aren’t sure how far they could spread, the best guess is they won’t get north of Oklahoma or past West Texas, LeBrun said.

In the meantime, the UT lab is testing a fungus that appears to spread quickly among crazy ants and, under certain circumstances, devastate them. The lab is still testing whether the fungus could harm other creatures.

The UT lab is also testing a type of tiny phorid fly that could be lethal to crazy ants. The fly would swoop in, plant an egg in the head of a crazy ant, then fly away; a few weeks later, the hatched larva finishes eating the ant’s brain and crawls out of its skull.

A similar phorid fly helps keep fire ants in check by disrupting their ability to forage. But LeBrun said the flies’ success in curbing crazy ants will depend on how effectively the flies disrupt the ants’ foraging pattern.

The work is promising, LeBrun said. But, he added, until it is proven successful, “There is no silver bullet.”