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Zapping mosquitoes away

High-tech traps may look cool but old-school methods work better

With summer heat, mosquitoes are more annoying than uninvited guests at barbecues and backyard parties. They not only cause itchiness but may trigger allergies or even spread diseases. It is advisable to learn how to choose from mosquito-eliminating products available rather than jumping to the first high-tech looking electronic bug-zapping devices.

Bill Rayburn of Hassett Ace Hardware in Palo Alto said it depends on whether there is standing water in your yard to determine what kind of mosquito-fighting products you will need.

"If you have standing water in your backyard, it's better to use mosquito dunks," Rayburn said.

Mosquito Dunks are made from soil bacteria and are considered an all-natural biological control product which can kill mosquito larvae in water.

For households without standing water, Rayburn said one option would be citronella candles, which are made of oil extracted from citronella grass, with a scent that can repel mosquitoes. Burning citronella candles or mosquito coils containing allethrin work best if there is relatively little wind, according to the statewide Integrated Pest Management Program of the University of California.

The UC Pest Management Program suggests trapping mosquitoes with a mosquito magnet, a device that attracts and captures the insects by releasing carbon dioxide and other attractants, like Ocetnol, a chemical that mimics human breath. Using Ocetnol in the mosquito magnet can attract 10 times the amount of mosquitoes than using it without the chemical, according to mosquito magnet manufacturers.

Not all traps are successful at eliminating mosquitoes. The UC Pest Management Program warns that electric bug zappers may be counterproductive, because many of the insects killed by these traps prey on mosquitoes. The way bug zappers work is that bugs are attracted to the UV light inside of them and then are electrocuted.

Megan Sebay, Public Health Education and Outreach Officer of San Mateo County, expressed a similar view on bug zappers.

"These will kill any insect that enters them, but they're not likely to reduce the mosquito population in your backyard, " said Sebay. "Mosquitoes detect their food source by smell and by sensing the carbon dioxide from your breathing and the warmth from your body. They are somewhat attracted to light, but a hungry mosquito will probably bite you rather than go into the trap."

"There have been some studies on this, and overall the evidence suggests that electric insect traps are a lot more efficient at killing nonbiting insects than actual mosquitoes."

The other problem is that traps that use light or any other attractant tend to draw in more insects than they kill, increasing the number of flying insects in your backyard, she added.

Sebay also dispelled some myths. She said the following practices do not work to repel mosquitoes:

dryer sheets, DIY insect repellents, perfume, lotion, baby oil, coconut oil, vitamins, garlic, special diets, bracelets, fragrant plants, candles, bathing, not bathing, or hanging plastic bags of water.

Here are some things she said do work: insect repellents registered by the Environmental Protection Agency, spatial repellents like clip-on devices, insect-repellent clothing (DIY with a permethrin spray or purchased pretreated), covering up with clothing, using a fan to create an air current, and using window screens to keep mosquitoes out.

The Centers for Disease Control recommends using EPA-registered insect repellents, especially now with concerns about the spread of the Zika and West Nile viruses. Repellents registered with the EPA have been tested for safety and effectiveness, Sebay said.

"Unregistered products only have been evaluated for basic safety, not for efficacy against mosquitoes," Sebay explained. "These products don't work as well or don't last as long as registered insect repellents."

"The very best way to prevent mosquito bites is by preventing mosquitoes." She said. San Mateo County has "a very good proactive mosquito control program" with nine full-time vector control technicians plus seasonal staff treating tens of thousands of water sources throughout the county. She said it's important for residents to "help us out by eliminating standing water on their own property. A few ounces of water can breed hundreds of mosquitoes in less than a week in warm weather," she said.

Crystal Tai is a freelance writer for the Palo Alto Weekly. She can be emailed at

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