This week's bone-chilling cold comes with a bonus. Long Islanders just have to wait for the payoff.

It turns out the frigid days and nights may bear fruit in months to come. Real fruit, in fact, and vegetables too, because farmers actually applaud freezing temperatures at this time of year, says Joseph M. Gergela III, executive director of the Long Island Farm Bureau.

"The deeper the frost goes, the better for the soil," diminishing some diseases and pest populations and softening the soil, so it's easier to plow come spring, says Gergela, a former potato farmer. Frost "does a lot of good things" for farmers and the backyard gardener, he said.

Since Tuesday, the temperature in Islip bottomed out at 5 degrees and never topped 24, according to the National Weather Service.

Hibernating mosquitoes, some destined to pass along West Nile virus, and ticks, some of them Lyme disease spreaders, can take a hit in frigid cold, though it will take more than this cold spell to make a dent in most species, says Laura C. Harrington, entomology professor at Cornell University.

Indeed, mosquitoes "are good at surviving," says Scott Campbell, chief of the arthropod-borne disease laboratory with the Suffolk County Department of Health Services.

Yes, a cold spell now will certainly lead to "some mortality," he said. But cold at this time of year "is just one part of the puzzle," he said. A dry spring could make for "a double whammy," further diminishing the mosquito population, he said, while a wet spring would hasten egg hatching and larvae development.

Even with a lower number of winter survivors, an early, wet spring would likely mean a longer mosquito breeding season and "several more generations," says Jody Gangloff-Kaufmann, community coordinator of the New York State Integrated Pest Management Program in Babylon.

Still, Harrington points to one new kid on the mosquito block -- the Asian tiger -- which might be knocked back by this week's cold. As temperatures globally have risen, that mosquito, which transmits West Nile virus to humans and heartworm to canines, has been "gradually moving northward" and "getting a foothold on Long Island," she said. Even this one cold spell has the potential "to really make a difference" on this small population, she said.

Looking ahead to next week, the bad news for farmers and public health officials is that temperatures are forecast to bounce back to the high 30s and 40s.

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The good news? That's expected to be "a brief warm-up" before a cold front is forecast for week's end, said David Stark, weather service meteorologist in Upton.