The telltale sound of summer in Rome used to be the clapping of plastic tables on the cobblestone streets as restaurants prepared to serve dinner under the stars. Now there's also the whine of buzzing mosquitoes. Those patrons intrepid enough to venture outside these days have to gobble down their bucatini before the insects--specifically, the Asian tiger mosquito--eat them alive. The bug arrived three years ago at the port of Genoa in a boatload of secondhand tires from Southeast Asia and apparently took to Italy's hot, humid climate--it's since spread as far south as Naples.

The mosquitoes are so aggressive--one can bite 10 times in succession, leaving large swollen welts that sometimes require lancing--that they're endangering the Italian al fresco tradition. Restaurants now brag about their use of pesticides on the cobblestones and shrubbery. People are putting up screens over their windows or, if they can afford it, buying air conditioners (sales have nearly doubled in the past two years). Worst of all, Italian men have even taken to wearing socks "even when it's brutally hot out," says Ugo Paglio, owner of the Roma Sparita restaurant.

Health officials are worried because the tiger (Aedes albopictus) is known to spread 17 different diseases, including West Nile, dengue and malaria. The bug's bite alone can cause fever in children. Rome has urged residents to check garden pots for standing water and to clean their balconies of debris that might collect water, where the bugs breed. So far the pests are winning. "The mosquitoes will reach epidemic proportions unless citizens start doing their part," says Massimo Tabacchiera, president of the city's environmental department. Now health officials spray the city at night; residents often wake up to find their balconies covered with tiny dead bugs. Few are complaining. The idea of a summer without socks is well worth it.