A threatening herd of Tawny crazy ants continues to spread across the southeastern United States. Dubbed "crazy" because of their unpredictable behavior and tendency to swarm, experts say they are a threat to the local ecosystem as well as expensive electrical wiring and circuits.
"You can stick your hand on the ground and they'll swarm all over and you'll look like a zombie," Austin resident Bill Leake told CBSNews.com. He first noticed the reddish-brown ants on his 10-acre property about five years ago. The property has always been infested with red fire ants, he says, but then one morning he noticed a long trail of much smaller ants.
"I thought nothing of it, but I started seeing more and more of that stuff," he recalls. "Within a few months we noticed we weren't being bit by fire ants anymore, but we also started noticing that those little ants were everywhere, in quantities far greater than we'd ever seen ants before.
First sighted in 2002, the tiny crazy ants were formally identified in 2012 as Nylandia fulva, a species indigenous to northern Argentina and southern Brazil. Scientists believe the ants were inadvertently transported here by people traveling from South America.
In the U.S., they are often referred to as Rasberry crazy ants, named for the Houston pest control operator who first spotted them. At first, "it was just something that looked a little different," Tom Rasberry told CBSNews.com. "The following year the numbers built from a few thousand to hundreds of millions."
University of Texas research assistant Ed LeBrun says they have since spread to about 50 counties across Texas, Florida, Mississippi and Louisiana, reports USA Today. They nest everywhere from crawl spaces and walls to electrical wires and small circuits. Researchers at Texas A&M University say they cause about $146.5 million in electrical damage each year.
When Leake called a pest control company to deal with the crazy ants, the first manager tried to treat them with the usual fire-ant pesticides and bait, to no avail. After a few others failed to recognize the difference, Leake showed them a website explaining that typical treatments are no match for crazy ants. They must instead be managed with termite-strength pesticides.
As they continue to spread, the crazy ants are a threat to the southeastern ecosystem. Rasberry estimated that they kill 90 to 95 percent of insects and reptiles, as well as birds, on the properties they populate.
Even when he is able to eliminate them from an area, Rasberry said, they quickly return. The crazy ants are so hard to contain, LeBrun explains, because they form a network of colonies to create a super colonies. Red fire ants are easier to control because they form individual colonies with distinct boundaries.
The crazy ant follows a long line of ant invaders, LeBrun says. The first on record was the Argentine ant, which came through the port of New Orleans around 1891. The black imported fire ant was the next to arrive, first spotted in Mobile, Ala. in 1918. By the 1930s, the red fire ant staked its claim in the area. It has dominated ever since.
In a study published in April, researchers from Texas A&M University found that fire ants are able to fend off crazy ants in most situations. But that shifts when crazy ants are restricted to a low-sugar diet, as happens when fire ants consume most of the available food. When consuming a low-sugar diet, crazy ants become stronger and more aggressive, and able to defeat the fire ants.
When UT researchers recently investigated two crazy any invasion sites, they found the red ant population decimated -- a sign that the crazy ant may quickly reign supreme in the southeastern region.
According to USA Today, the crazy ants are also causing ecosystem problems in South America, where they have killed off other ant species and small animals; attacked the eyes, noses and hooves of cattle; and dried out grasslands.
On his acreage in Travis County, Leake has already seen the crazy ants take over parts of his vegetable garden, knock out other insect species and infest a few cars. But they have yet to wreak havoc on any expensive electrical items, he says.
And as far as Leake is concerned, taking over the red fire ant population, at least on his property, is a welcome change.
"It's wonderful," he says. "It's nice to walk around my yard barefoot. They may run over my feet, but they won't bite me."