To the uninitiated, New York City might have seemed on the verge of civil war. Police were evacuating Central Park, low-flying helicopters buzzed overhead carrying deadly sprays, and officials urged parents to keep their children indoors.
But the city that prides itself on being tough enough to survive anything was bracing for an invasion of a mite-sized peril, the West Nile virus, the potentially fatal mosquito-borne disease that claimed seven lives last year and sparked fears of an epidemic.
On Monday helicopters sprayed the city's green heart, Central Park, with pesticide after mosquitoes carrying the virus were discovered there. Tonight helicopters will sweep again over Manhattan, spraying a huge swathe of the densely-populated island, and Brooklyn.
The Mayor of New York, Mr Rudy Giuliani, even decided to cancel a New York Philharmonic concert and close the park down rather than risk any lives.
"The idea of having 30,000 people there would have been risking the odds," Mr Giuliani said. But the man who took on the city's mob didn't appear too concerned.
New Yorkers and tourists alike seemed to be following his lead. Packs of schoolchildren competed yesterday for space on bustling sidewalks with hot-dog vendors. Cyclists were still circling the park's border weaving between joggers.
"We read about it this morning in the newspaper and my wife always takes certain precautions," said an English tourist, Mr John Brambley, as his wife busily sprayed herself with anti-bug mist for their stroll through the park. "We're not really that worried, though," he added after only two days in the city.
Nearby, buying ice-cream in the park for her two children, Ms Lisa Masucci was taking a more relaxed attitude to the bug war.
"It doesn't really matter to me where we are. I feel like I have no control over it," the New Hampshire visitor said. "But we'll be staying inside at night." Last year bug fever swept through the city after dozens were infected by the disease and seven mostly elderly residents died from the virus.
The West Nile virus can cause encephalitis - inflammation of the brain - or meningitis. Outbreaks have occurred before in Egypt, Asia, Israel, South Africa, parts of Europe and Australia. But last year's outbreak was the first time it had been found in the US.
That has prompted New York to take the fight to the mosquitoes. Advertisements on the subways and local television stations ask residents to help keep the city mosquito-free.
Early-warning tests - including 120 traps at more than 70 sites throughout New York - are allowing officials to monitor the virus. The New York State Department of Health has already confirmed evidence of the virus in two other pools of mosquitoes trapped on Staten Island and in Queens.
With a typical New Yorker's nonchalance, a horse-and-carriage driver, Mr John Michnej, wasn't letting that worry him.
Standing at the southern end of Central Park yesterday with his horse, Lisa, waiting to give tourists a ride, he said none of his customers had even complained.
"If they don't spray and someone dies, what happens then? Everyone starts complaining."