KEY HAVEN, Fla. — To live here, along this chain of tiny islands, a place vulnerable to hurricanes and steeped in the lore of piracy and smuggling, requires a blend of carefree eccentricity and go-it-alone grit.

So when, several years ago, the Florida Keys Mosquito Control District offered up the peninsula of Key Haven, a tiny suburb of Key West, for the first United States test of genetically modified mosquitoes built to blunt the spread of dengue and Zika, it was only a matter of time before opposition mounted.

Today, even as federal officials have told pregnant women to stay away from parts of Miami-Dade County because of the Zika virus, Key Haven’s hardened position against the trial — or the experiment, as they call it — is hard to miss amid the bougainvillea and hibiscus flowering on lawns here. “No Consent to Release of Genetically Modified Mosquitoes,” red-and-white placards declare.

“People here can survive what nature throws at them,” said Gilda Niles, 64, who arrived in Key West from Cuba in 1967 and moved to Key Haven in 1980, when it was just a plot of earth with cheaper land, water on three sides and more space. “Hurricanes, bring them on; long-timers here seldom evacuate. Mosquitoes, well, that’s the price of paradise. Zika, this too shall pass, like dengue. But science and government, I’m not so sure about.”