Correction to This Article
A graphic with a May 2 article about tiger mosquitoes incorrectly said that the chemical DEET kills mosquitoes. Repellents containing DEET repel the insects but do not kill them.

Urban Pest Will Soon Be Out for Blood

By Elizabeth Williamson
Washington Post Staff Writer
Tuesday, May 2, 2006

It shuns green space and clear water for crowded urban cover. Day and night, it goes for blood, targeting the tender flesh between the ankle and the knee. It penetrates most protection and resists high-tech efforts to contain it.

It's the Asian tiger mosquito, a distinctly urban pest plaguing patios in the seat of power. And this year, it's early -- with the season's first swarms expected within two weeks.

Over the past three summers, the tiger mosquito has grown to dominate this region's more than 60 mosquito species. Skittish and fast and able to breed in a bottle cap, the insect has proven as tough to eradicate as it is to swat, dealing mosquito abatement experts a new and nasty challenge.

"It has changed the complexion of residential mosquito control," said Roger Nasci, research entomologist at the federal Centers for Disease Control and Prevention. "The tiger mosquito is predominantly a container mosquito . . . and its backyard production means they're very difficult to manage."

Since entering this country from Japan in 1985, the tiger mosquito has spread from the steamy South steadily north and west. It has strengthened its grip on this region -- especially the District and urban Montgomery, Fairfax and Prince George's counties -- because of its preference to breed in niches where most other mosquitoes don't -- tire treads, cans, flowerpots, sandbox toys, even the wet wrinkles of plastic bags. Other mosquitoes opt for wide-open wetlands.

Before the breed arrived, "very few native mosquitoes were able to live in abundance in the metro and suburban areas of D.C.," said Cyrus Lesser, Maryland's chief of mosquito control.

Tiger mosquitoes can carry such diseases as West Nile and encephalitis. But they are better known for chasing the residents of entire neighborhoods from their back yards.

"The only real solution to the Asian tiger is source reduction -- you've got to get rid of the breeding sites," said Jorge Arias, mosquito control chief for Fairfax County. "The power of this mosquito is unbelievable."

Working in West Africa several years ago, Allison Hudgins evaded swarms of winged marauders every night. But she had to fend off daytime bites at her Alexandria duplex. She slapped, missed and figured her neighbor's ratty yard was spawning something new.

In 2001, Hudgins and her husband, Coley, moved to Northwest Washington. About the same time, tiger mosquitoes moved in, too. Larvae typically are imported inside a container. They hatch within two weeks, and then the females fly forth, bite and multiply.

So it went on Legation Street, which by last summer had a near-biblical tiger problem. The insects fly day and night, low and fast -- biting adults most often on the legs and children all over. "Ten minutes and they're buzzing around your legs," Hudgins said. "After that, it's like a game. . . . How am I going to smack that next mosquito?"

One neighbor dropped organic insecticide tablets down the sewers. Another put out water sources to lure them and kill them. They tried creams and candles, foggers and zappers. They talked about pitching in to get a colony of mosquito-eating bats. The District does not spray for mosquitoes but will drop commercial larvicide tablets into trouble spots. But that doesn't work well for tiger mosquitoes.

Hudgins bought a $100, propane-powered gizmo that sucks mosquitoes from the air. "We caught maybe 10," she said. "We threw it away."

Every few days, Hudgins -- wearing wilderness-strength repellent -- dumps water from the backyard grill, the kayak, the recycling bin, sandbox toys. "I'll spray the yard down, spray myself down and the kids." She knows some people frown on that, but on Legation Street, she said, parental failure is defined as "a big bite on your kid's forehead."

This month, the Hudginses sold their house. "We didn't have to disclose the mosquitoes," she said. The family is moving to Panama, where the bugs "can't be any worse than here."

Tiger mosquitoes arrived in Houston in 1985, stowaways inside used Asian tires prized by recyclers for high rubber content. The insects have ridden old tires across the nation.

A first port of call was New Orleans, where in sodden post-Katrina neighborhoods, they bite at a rate of up to 75 a minute, about 30 times the rate on Legation Street. By 1990, tigers were ruining Midwestern cookouts from Chicago to Cleveland. Five years ago, they were nibbling the legs of office workers in the Los Angeles port.

In this region, tiger mosquitoes appeared in a tire yard in 1987 in Baltimore, which, along with parts of Anne Arundel and Prince George's counties, remains one of the region's worst-infested areas. The District, Fairfax, Montgomery and Howard started slapping about five years ago. Today, tiger mosquitoes are found in 27 states, a figure some scientists say is too low.

In an ad-hoc dump behind a strip mall in Prince George's, Jeannine Dorothy dipped her white ladle into the fetid interior of a tire, like a cook testing soup.

"Oh, yeah," the Maryland entomologist said, gazing at squirming S-shaped larvae. "These are bigger than I thought they'd be."

That means the bugs could be out in force within two weeks.

Dorothy offers to walk through back yards with homeowners, noting water that needs to be dumped. "It makes a huge difference," she said. But to work, the entire street's residents must sign up and take notes. Not many do.

So far, no other plan -- contraption, poison or predator -- has beaten the tiger mosquito.

Home insecticides work only if they are applied every day or two. Organic agents aren't practical for myriad small spaces. Birds, bats and frogs "don't eat enough," Lesser said. The mosquitofish loves tiger larvae but can't be stocked in a barbecue grill.

Not long after the breed arrived, Maryland entomologists hand-raised a strain of tough-sounding "cannibal mosquitoes" to conquer the tiger variety. A genteel breed that eschews human blood, they were taken from the lab to the mean streets of tiger country. Floating like hope into the ozone haze, they splattered on windshields and fried on the pavement. Birds ate the rest.

"It's a lovely animal," Lesser said. "But they don't seem to be very vigorous."

© 2006 The Washington Post Company