Because we’re hearing so much scary stuff about mosquito diseases, I’m in the market for a super-duper, big bug zapper for our backyard. My wife objects though, she says that those things don’t work and she hates the zapping sound. What’s the latest on mosquito traps? P.P., Heniker, NH

Bug zappers use ultraviolet light to attract mosquitoes to a metal grid where they are electrocuted or “zapped.” People that use bug zappers delight in showing off the hundreds of dead mosquitoes in their traps. The trouble is that the vast majority of those insects are not mosquitoes.

Bug-Zapping Light Traps Kill Very Few Mosquitoes

One study of typical bug zapper contents found that 89% of the zapped insects were midges, look-alike but harmless cousins of mosquitoes. The remainder were aquatic insects, beneficial insects, male mosquitoes (that don’t bite), and finally just 3% were female mosquitoes. Not all species of mosquitoes are even attracted to light. Bug zappers are more likely to attract insects into your yard that weren’t there in the first place. In another study, after 11 days of continuous operation, bug zappers failed to reduce the mosquito biting rate in the yards studied.

Carbon Dioxide Traps Are More Effective

All of this is kind of a moot point since bug zappers are old technology. In recent years, we have seen the emergence of new style of mosquito trap that uses much more than light to lure mosquitoes. Newer traps emit carbon dioxide (the stuff that we exhale) and heat to simulate an actual living breathing animal, or person. Some even add chemical attractants such as octenol that mimic animal scents. Mosquitoes that are attracted to the trap are either trapped on a sticky board or are suctioned by a fan into a holding container. Some traps operate on electricity but others use propane or batteries.

These traps do trap mosquitoes but many different factors can affect their success, placement and setup is crucial, and not all mosquito species are equally attracted. These traps are expensive and can require a lot of maintenance which is one reason why they are used most often by pest control professionals. But if you feel the need to buy a mosquito trap, buy one of these, not a bug zapper. Mosquito World reviews several of the newer models at their website.

Eliminate Breeding Sites Instead

Instead of buying traps to control adult mosquitoes in your yard, work on eliminating mosquitoes at the source, before they can turn into biting adults. Conduct a survey of your yard for standing water where mosquito larvae develop (see How to Eliminate Mosquitoes From Your Yard – Advice From the Pros). Eliminate or treat standing water in which mosquitoes breed, remove or thin heavy shrubbery to reduce mosquito resting places, and use personal repellents diligently.