By Jeff McMahon
Reprinted from Forecast Earth • August 6, 2008
It sounds like science fiction: a previously unknown insect with an appetite for electrical circuitry appears at a Houston-area chemical plant and marches toward the Johnson Space Center, defying human attempts to stop it with conventional weapons.
“I think we ought to be in panic mode,” said Tom Rasberry, the Pearland-Texas exterminator who was the first to battle the unidentified species that has informally taken his name: the crazy rasberry ant. “I’m not one of these people who panic about anything, but this is something that I really do think we should panic about it.”
Since the national media profiled the tiny frenetic invader in May, the ant has been documented in eight Texas counties, has caused an estimated $30 million in damage, and is said to be colonizing a half mile of new territory each day. As it goes, it displaces native ants, suffocates birds by crawling into their nasal passages, and shorts out wiring. In July, the Environmental Protection Agency granted Southeast Texas a crisis exemption to restrictions on fipronil, a powerful pesticide. Yet the ant marches on.
And just as science fiction movies return to television every few years, the alarms sounded by scientists, government officials and exterminators echo previous warnings. Like the crazy rasberry ant, the Argentine ant arrived by freighter, spread rapidly across the American south, displaced native species, chewed on electrical wiring, and defied conventional pesticides. Several species of imported fire ants followed a similar course.
And who could forget “killer bees,” whose terror Americans have anticipated for more than three decades ? Irwin Allen’s 1978 movie “The Swarm” captured those expectations battled them. The movie’s tag line: “It’s more than a speculation — it’s a prediction!”
Now they’re here. Africanized honey bees, known for their short temper and swarming attacks, arrived in Texas in 1990 and have been documented in half of Texas counties. It’s the policy of Texas A&M University to “consider the entire state as Africanized” when educating the public about bees. But Texans and killer bees have largely been getting along. Since 1990, there has been one documented death from an Africanized honey bee attack in Texas, and two deaths from honey bees believed to have intermixed with the Africanized variety, according to university officials. Typically, two Texans die each year from encounters with normal honey bees.
Nonetheless, Texas A&M officials think it’s best to keep the public on edge: “The best policy is to promote safety,” Tanya Pankiw, a professor of entomology, said in a statement posted on the university’s website. “Teach the public to be cautious around all bees.”
Cry for Me, Argentina
It may be an unfortunate side effect of that caution that the public finds invasions anti-climatic, even when biologists consider them devastating. In California, homeowners may find Argentine ants pesky, but biologists consider them far worse.
“It’s a terrible invasion,” David Holway, an ecologist at the University of California San Diego, said of his state’ s perva sive invader. “They pretty much wipe out all of the native ants where they’re introduced.”
Argentine ants are prime suspects in the horned lizard’s disappearance from Southern California. The lizard feeds on larger ants the Argentine ant displaced. But few other grave impacts on vertebrates, including humans, can be pinned on the Argentine ant.
“Trying to understand what happens when all the native ants disappear is extremely difficult,” Holway said.
None theless, studying the Argentine ant may help scientists anticipate the crazy rasberry ant. Often these invaders come from competiti ve e nvironments where evolution teaches them aggression.
“It’s kind of like growing up in a rough neighborhood. It makes you street smart and tough,” Holway said.
Invasive ants also may benefit from less genetic diversity. In Argentina, different colonies of the same species fight each other for territory, keeping each other in check. But members of a single colony who arrive in a new territory can establish a vast supercolony. If you pick up an Argentine ant on the UC San Diego campus and drop it 500 miles away at UC Berkeley, the Berkeley ants will welcome it as a nestmate, Holway said. It would take a mighty can of Raid to wipe out that colony.
Houston, We Have a Problem
When Tom Rasberry, 51, first spotted an unfamiliar ant at a small chemical plant in Pasadena, Texas in 2002, he didn’t think much of it. “But in 2003 that same ant went from very small numbers to literally billions and billions of them,” he said.
Since then, Rasberry has chased his tiny namesakes from dozens of houses and businesses, including the Johnson Space Center, where their affection for wiring could threaten national security. Rasberry charges homeowners about $1,200 to oust the ants, compared to normal pest control costs that average $250 a year.
“You can’t imagine, you have a customer call and they’re filling up a vacuum cleaner bag every day out of their house,” he said. “Full of ants, every day.”
Matt Goldey isn’t sure the ants that invaded his Rowlett, Texas, home were crazy rasberry ants, he said, but they drovehim crazy.
“They’re the stupidest, strangest ants I’ve ever seen. They don’t bite, and they don’t get in our food. They just march all over the damn house,” said Goldey, 35, an information technology professional. “I’ve sprayed Ortho Home Defense Max all over the place — they just do cannonballs into puddles of it and laugh at me. I’ve spread broadcast insecticide pellets all over the yard — no joy.”
Goldey called Terminix, which expelled the ants from his house after four visits, he said via email. But Tom Rasberry doubts Goldey had crazy rasberry ants, because they don’t leave that easily.
“The homeowners are going into these box stores and buying chemicals,” Rasberry said, “and that doesn’t work. Next thing you know they’ve dumped 400 pounds of pesticides in the yard. Then you get runoff into the water tables and everything.”
And that may be the biggest problem with invasive insects.
“It’s not the ants themselves,” Holway said, “but our response to the ants.”
How to fight an ant invasion
- Think Like an Ant: “Try to identify what they’re going after,” Holway said. “Is it food, is it some kind of nest site? If you can eliminate that, then that will largely eliminate their incentive for coming into your house.”
- Clean the House: When myrmecologists — ant scientists — say ants will not be attracted to a meticulous house, they mean meticulous to ant standards, not human standards. Those little nooks and crannies where crumbs can hide may elude us but offer a feast to ants.
- Mind the Gap: Seal any cracks or crevices that ants can use to enter your house. You can use silicone caulk for a permanent barrier or petroleum jelly for a temporary one. See that gap under your door? It’s a potential ant superhighway. “Effective door sweeps that close the gap between the bottom of exterior doors and the door sill are essential,” said Thomas Green, president of the Integrated Pest Management Institute of North America.
- Turn off the Sprinklers: If you live in a dry climate, ants have likely come to your yard and your home looking for water. Scientists at UC San Diego were able to drastically reduce ant populations on irrigated land by shutting off the irrigation. “In California, what I always tell people is stop watering your lawn. Use less water and you’ll have less ants,” Holway said. “People unfortunately don’t like to hear that, but it’s true.”
Try Natural Insecticides and Repellants: The University of Florida maintains a list of botanical insecticides that have some environmental advantages, such as rapid breakdown. Some, like nicotine, are nonetheless dangerous. They include citrus oils, neem oil, diatomaceous earth and sulfur. Find Florida’s list at http://edis.ifas.ufl.edu/IN197, but be advised not all may deter your invaders. “Often that’s very species specific, so what works for one ant might not work for another,” Green said. Some types of ants are also said to avoid Borax, basil, bay leaves, catnip, cayenne, cinnamon, coffee, camphor, peppermint, vinegar.
LifeWire is an online content provider launched by The New York Times Company to create and distribute lifestyle articles to top Web publishers. This article first appeared at Forecast Earth, original url:http://climate.weather.com/articles/antinvasion081408.html