Q. I thought I read somewhere that bug zappers don’t really work. My neighbor’s zapper is driving me crazy with that ZZZZT noise all night. I’d like to show him proof that all he’s doing is annoying his neighbor. Any facts?

A. Yes, there is some scientific data on the usefulness of bug zappers, but first we need to distinguish between the bug zappers that homeowners use in their yards to (hopefully) kill mosquitoes, and the commercial insect light traps that pest control professionals use mostly in restaurants, food plants, and warehouses. These expensive commercial traps are used mainly to kill house flies and they do work. The relatively inexpensive backyard bug zappers kill plenty of flying insects, just not mosquitoes.

Bug zappers use ultraviolet light to attract mosquitoes to a metal grid where they are electrocuted or “zapped.” People that own these traps swear by them. They point to the piles of dead insects that they empty out of the trap each morning. And those insects do look like mosquitoes. But mostly they are midges, harmless fliers that do not bite and are considered beneficial.

Bug zappers actually attract and kill very few mosquitoes. Instead, the ultraviolet light draws hordes of insects into the yard that wouldn’t have been there otherwise. Yard zappers have never fared very well in research tests. One study found that 89% of the zapped insects were midges; only 3% were female mosquitoes capable of biting. The remainder were aquatic insects, predators, and insect parasites. In another study, after 11 days of continuous operation, the zappers failed to reduce the mosquito biting rate in the test yards.

Instead of buying bug zappers to control mosquitoes, people would be better advised to (1) eliminate or treat standing water in which mosquitoes breed, (2) change, reduce, or shield outdoor lights, (3) remove heavy shrubbery to reduce mosquito resting places, and (4) use repellents.