Are Bug Zappers Bad News?


Bug zapper
Bug zappers emit a high-intensity UV light that attracts all insects, indiscriminately killing bugs, including pollinators, that can be beneficial to our environment. Flickr (CC BY 2.0)

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There are many ways to catch a fly. Those of us who grew up in the '80s will remember the brightly colored bags everyone perched on their lawns come summertime to coax bugs in by the handful and trap them inside. Of course, sprays, swatters or a handy pair of chopsticks (if you're really looking for a challenge) can also do the trick.

It turns out, however, that one of the most popular tools for staying bug free may do more harm than good.

We're talking bug zappers. They obliterate flies and other critters by emitting a UV light that indiscriminately attracts flying insects, electrocuting any winged object that comes into their path.

There are a number of reasons that backyard grillers and chillers should ditch zapping machines, says Jonathan Day, associate professor of entomology with the University of Florida's Institute of Food and Agricultural Sciences.

Back in 1997, Day estimated that 71 billion non-target insects are slaughtered by these devices in the U.S. alone every year. Most were beneficial beetles, moths, ants and midges along with parasitic wasps that control other insect pests. Several other studies from that same time period, including one from the University of Delaware, found similar results. With the drop in insect populations that is being observed around the world, indiscriminately zapping bugs is bad environmental policy.

In an August 2019 interview, Day still maintains that the biggest threat from zappers is what he calls “non-target impact.” The UV lights the devices use to lure mosquitoes in are also likely to attract a number of other bugs. That includes wasps and others that serve an important purpose by killing off pests.Most are beneficial beetles, moths, ants and midges along with parasitic wasps that control other insect pests. “Mosquitoes are a very small part of the population attracted to bug zappers,” Day says.

When an insect is zapped, the devices send bacteria, along with bug particles that could be carrying viruses, flying into the immediate area, according to a study conducted in 2000 by researchers at Kansas State University. Bacteria that bugs pick up on the surface of their bodies or accumulate in their digestive canals do not get zapped. Instead, they survive on the small particles of electrocuted bug body that go hurtling through the surrounding area when an insect is electrocuted. And what goes flying into the air has to land somewhere, right?

So there are a number of reasons to ditch zapping machines, says Day. The health threat of having a bug incinerated onto your burger, while completely unappetizing, is actually at the bottom of the list.

“I think that’s a very minor concern with bug zapper usage,” Day says. “That event is going to be a very rare one. It requires the bug zapper be hung over your picnic table and an infected fly to come into that bug zapper at the same time that your sandwich is sitting within range. It’s probably a lot more dangerous for you to have a fly walking over your food.”

The good news is that backyard enthusiasts have a number of other options for combating mosquitoes. Day says to wear athletic clothing that bugs can’t bite through, use a decent repellant and turn on the fan.

“Mosquitoes are poor fliers. There is nothing more effective than a fan.”

Next time you invite your friends over for a cookout, you may want to reconsider how you go about warding off bugs. A wise fella once said something about using honey.

This article was updated to include comments from Jonathan Day.

Last editorial update on Aug 23, 2019 04:00:38 pm.