At Ledford’s, our Charleston, Columbia, and Florence pest control experts are always on the look-out for new pests. We came across a myStatesman article recently that describes “crazy ants” – a kind of fire ant that’s causing lots or problems in the South. We thought we’d share:
“Hoping to underscore 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 actually 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 are now one of the main topics of study at the Brackenridge Field Laboratory, a University of Texas facility on Lake Austin Boulevard 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, then collect them a day later. The ants swarm in such vast numbers that the researchers didn’t even have to bait the tubes.
“An invasion of these can be so extreme,” LeBrun said, “that it’s hard to call it just a nuisance.”
Houston, we have a problem
Have you ever heard anyone talk wistfully about fire 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 are now found in 23 Texas counties, including Travis, Hays and Williamson, according to Texas A&M’s Center for Urban and Structural Entomology. LeBrun named, off the top of his head, crazy ant populations near Briarcliff (west of Austin), the Met Center (Southeast Austin), Convict Hill (South Austin) and McNeil High School (North Austin).
Before you panic: 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, then letting colonies sneak into potted plants or plywood or hay bales and hitch a ride.
Rock, paper, ants
Telling the story of the crazy ant requires bringing fire ants into the conversation.
They 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 does have 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. UT science writer Marc Airhart compares the situation to a game of rock-paper-scissors: crazy ants beat fire ants, fire ants beat other ants, and other ants beat crazy ants.
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.
If fire ants are rock, and crazy ants are paper, there are no scissors here.
All happy families are alike
Still, the old truism about a greatest strength also being a greatest weakness could apply to crazy ants. Again, a comparison with the rival fire ants is useful.
One type of fire ant spreads over great distances in part because, when a new queen is born, it flies off and either dies or establishes its own colony. But that colony doesn’t generally get along with other colonies. The single-queen fire ants tend to build their mounds and keep to themselves. That behavior limits cooperation between colonies, but it also buffers many fire ant populations against outbreaks of disease.
Crazy ants are difficult for precisely the opposite reason: Their colonies get along. They’re like one big, happy family.
Crazy ant queens don’t fly off to breed or die. Instead, they stay home and breed alongside other queens. LeBrun said having eight queens isn’t unusual, and researchers have even found upward of 100 of them in some colonies. The tendency to stay home slows the spread of crazy ants.
Nature might also 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.
But beware: when crazy ants arrive, they are probably at the leading edge of a “supercolony” of many, many nests – wave upon wave of reinforcements to send in if one nest is injured. LeBrun said the supercolonies he has studied tend to be circular and can be a kilometer or many kilometers in diameter.
A supercolony is susceptible to contagion, though. The UT lab is now 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.”
*Photo courtesy of wikipedia.org