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The Big Buzz About Mosquito Repellents

MIAMI (CBSMiami) - Would you stick your arm in a cage filled with 150 hungry Southern House mosquitoes, the very ones that carry the West Nile virus?

Well, thankfully you don't have to because researchers did just that to discover which mosquito repellents work the best.

Tons of lotions, potions, bracelets and sprays are on store shelves all claiming to be the best at keeping mosquitoes off you.    To test their claims, researchers put four of the products to the test.

Dr. Gabriel Hamer, a Clinical Assistant Professor with the Texas A&M University Department of Entomology, has spent the last eight years studying the West Nile virus in mosquitoes, birds and humans.

The Southern House mosquitoes used for the tests were bred at the university.

Researchers first established controls.  They counted the number of mosquitoes inside glass cages and documented their resting spots in relation to a white circular piece of filter paper.

The filter papers were then removed from the cages and used to simulate human skin. Researchers sprayed, rubbed and attached four products to four different papers and then put them back inside.

One of the products tested was 'Off,' an insect repellent with 15-percent DEET. Researchers also tried Bio UD, a new product, recently approved by the EPA, made from tomato plants. They tested 'Skin So Soft,' a lotion by Avon that many people have long-touted as a mysterious mosquito repellent. And a citronella-covered bracelet was also put to the test.

Dr. Hamer and his staff taped the product-covered filter papers on one side of the glass cage, and then blew into a mesh covering on top of the cage to disturb the mosquitoes. The insects swarmed around the enclosure before settling. Once they did, Dr. Hamer and his team counted the number of mosquitoes that landed around the products and the number of mosquitoes that flew to the other side of the cage, trying to get as far away from the products as possible.  The team ran the test three times and then calculated percentages to compare to the controls.

So, which one product repelled the most mosquitoes?

"I would say the DEET and Bio UD had very similar levels of efficacy," said Dr. Hamer.

Hamer said the Bio UD scored slightly better than the OFF, but the DEET spray came in a very tight second.

"Both of these products, when applied to these filter paper, no mosquitoes landed on that paper and they even stayed quite a ways away from that filter paper," said Hamer.

Other tests found the mosquito band and Skin So Soft also repelled mosquitoes, but didn't repel nearly as many as the other two products.

"The Skin So Soft moisturizing lotion used in this report is not intended to repel mosquitoes, is not sold for that purpose, and is not approved by the EPA as a repellent. Avon does offer several insect repellents, including Avon's Skin So Soft Bug Guard Plus line of products," said a statement sent by Avon's brand public relations senior manager. "These products are approved by the EPA for use as insect repellents, and they contain active ingredients that are effective deterrents against mosquitoes."

When asked if the citronella-covered bracelet was a product Dr. Hamer would use on his own two-year old, he said, "I'd probably prefer alternative products."

Researchers said the trial could not determine how successful the products may be with longer exposure.

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