Snap! Crackle! Pop! Electric Bug Zappers Are Useless For Controlling Mosquitoes, Says UF/IFAS Pest Expert

July 23, 1997

GAINESVILLE—If mosquitoes and other insects are taking a bite out of your summer fun, don’t bother with one of those electric bug zappers, says a University of Florida pest control expert.

“They are a total waste of money. Bug zappers will not control mosquitoes or other biting insects such as horseflies, dogflies or deerflies,” said Jonathan Day, associate professor of entomology with UF’s Institute of Food and Agricultural Sciences.

“They simply do not work as advertised. In fact, bug zappers actually make things worse by attracting more mosquitoes into your yard, and they end up killing thousands of beneficial insects that don’t bother people.”

He said the devices have been on the market for more than 30 years, and prices range from $30 to more than $200 for those sold in upscale stores and catalogs. They all have an ultraviolet light that attracts bugs to an electric grid that electrocutes them.

“When people buy one of these bug zappers, they want to see and hear bugs fry. That’s one of the great attractions of these things. You hang them in your yard, and they really put on a show. As the bugs hit the electric grid, they arc. There are a lot of light flashes and snap, crackle and pop sounds. That’s what people get for their money.”

While the UV light in these bug zappers draws a wide range of insects, mosquitoes and other biting insects are more attracted to the carbon dioxide exhaled by people and pets. They’re also attracted to carbon dioxide that is passed through human skin.

“The main reason bug zappers don’t work is that mosquitoes are extremely sensitive to carbon dioxide,” Day said. “They see the UV light in your yard, but once they pick up even the slightest trace of carbon dioxide from people, they change direction and zero in on the source of that odor. They are expert at detecting carbon dioxide at levels as low as 50 parts per million.”

Some zappers claim to interrupt the mosquito breeding cycles, and others promise to control pests over an acre or more. Both of these claims also are false, Day said.

Even some of the new electric bug zappers that have been fitted with an octenol packet — which he described as “the latest marketing gimmick” — are virtually useless for controlling mosquitoes. Compared to the powerful attraction carbon dioxide has for mosquitoes, octenol is a minor chemical insect attractant and will not improve the overall performance or effectiveness of the device.

Day said tests at the UF/IFAS Florida Medical Entomology Laboratory in Vero Beach show that thousands of beneficial insects — not mosquitoes — are the main victims of the electric devices. Out of some 10,000 insects destroyed by one bug zapper during a one-night test period, only eight were mosquitoes.

He estimates 71 billion nontarget insects are zapped by these devices across the nation every year. Most are beneficial beetles, moths, ants and midges along with parasitic wasps that control other insect pests.

“Sure, some people say the only good bug is dead bug, but they don’t understand the relationship of insects to the overall ecosystem,” Day said. “Whether it’s for pollination or food for birds and other vertebrates, the vast majority of insects are beneficial. We would be in bad shape if we killed all of our insects.”

To ward off mosquitoes and other biting insects in the yard, Day recommends using an insect repellent containing an active ingredient called deet. He said it’s the most effective repellent developed in the past 40 years. Wearing protective clothing or simply going indoors also are options for battling pesky insects.

Since mosquitoes breed in standing water, Day recommends emptying birdbaths, kiddy swimming pools and other water sources in your yard or adding a briquette with altocid to kill mosquito larvae. Neighborhood spraying programs by city or county governments produce temporary relief from mosquitoes, usually less than 24 hours, he said.

Day also discounted the value and effectiveness of various ultrasonic devices. “There are ultrasonic devices to control or repel everything from cockroaches to rats, and none of them work. They’re one of the biggest rip-offs on the market,” he said.

And, he added, citronella plants have no repellant benefit.

“While citronella oil is a repellant, it must be reapplied frequently,” he said. “Citronella candles contain the oil in the wax. As the wax burns off, citronella is released in the smoke. However, in order to derive any benefit from citronella candles, you have to stand in the smoke.”

Andrew Myers, vice president of administration for North Palm Beach-based Deejay Corp., which manufactures and markets electric bug zappers under the Stinger brand name, said the company stands by all the advertising claims on the box of its product.