Taking a bite out of mosquitoes

A new method sprays them with garlic oil

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August 12, 2006|By JOSEPH SJOSTROM | JOSEPH SJOSTROM,CHICAGO TRIBUNE

Bats. Electric bug zappers. Tiny fish. Insecticides.

As mosquito-control devices, they all work. And they all don't.

The quest to repel mosquitoes has led people to try some unorthodox methods. But a nature center in Itasca, Ill., tried one this summer that was particularly pungent: garlic.

It's a garlic-oil product marketed as harmless to the environment but effective in killing and repelling mosquitoes. But, like most repellents, it showed mixed results.

Fred Maier, director of the Spring Brook Nature Center, said his workers sprayed garlic oil on an acre of woods June 13 and July 6, then used two traps -- one placed on the sprayed land and one on unsprayed land. The first test found fewer mosquitoes in the sprayed area than in the unsprayed area. A second count found just the opposite.

It wasn't a total loss, however.

"It made the woods smell like a really good Italian restaurant for a while," Maier said.

So the quest continues.

Some people buy electric bug killers; some think insect-gorging bats or purple martins work best. Others choose home remedies -- fabric softener, bath oil, pure vanilla, vitamin B or a combination of Epsom salts, beer and Listerine.

So it should be no surprise that Itasca officials, reacting to mosquito complaints from visitors at their nature center, wanted to try something like garlic oil.

While Maier said they'll do one more test before deciding whether to use the product regularly, the manufacturer claims that its product works best on open fields and is unsuitable for woodland application, like the 50 acres of woods and wetlands that Itasca's nature center sits on.

The product, called Mosquito Barrier, is produced by Garlic Research Labs, of Glendale, Calif. Norman Sutcliffe, the company's national sales manager, could not name a scientific study proving that garlic repels mosquitoes. But he said countless customers, some of them listed on the firm's Web site, attest to its effectiveness.

One of them, Lonene Edwards, treasurer of Poinsett County, Ark., and secretary-treasurer of the Poinsett County Agricultural Fair Association, said her northeast Arkansas community suffers summer-long invasions of mosquitoes, but application of garlic oil to the county fairgrounds starting two years ago eliminated the problem.

"You get eaten alive if you go outside after dark around here," Edwards said. "After they sprayed the fairgrounds, there was like a line you'd cross where there were mosquitoes on one [the unsprayed] side and none on the other."

Another user is Guilford, Conn., a community on Long Island Sound where mosquitoes breed on the shoreline. Dennis Johnson, the town's health director, said garlic oil has kept mosquitoes there in check for the past three years.

Robert Novak, a medical entomologist with the Illinois Natural History Survey, said that especially in times of danger from West Nile virus, people should not rely on products that haven't been scientifically tested and proven effective.

Lee Mitchell, a biologist with the Toledo [Ohio] Area Sanitary District, wrote an article in 1993 for The Vector Control Bulletin of the North Central States summarizing the effectiveness of various mosquito-control strategies. He said he has updated the article with current sources so the article remains accurate.

He wrote that scientific literature indicates that bats eat a lot of flying insects but very few mosquitoes (0.7 percent of their diet in one study). A study of purple martins, a bird species long thought to be voracious consumers of mosquitoes, showed their diet includes wasps, butterflies, stinkbugs and dragonflies, but no mosquitoes, Mitchell wrote.

Electrocution traps kill every bug that flies into them, Mitchell wrote, though studies have found that mosquitoes constitute just 6 percent of the kill.

Mosquito fish, or Gambusia affinis, a tiny fish that feeds on mosquito larvae on the surface of ponds, can be very effective, Mitchell said in a phone interview.

But he said the fish don't eat one species of mosquito that spends its larval stage underwater attached to stems of cattail plants instead of on the water's surface.

Mitchell and other authorities say the best strategy for mosquito control consists of eliminating as much of their breeding pools as possible, treatment of breeding pools with chemicals or mosquito-eating fish, and use of personal repellent products containing DEET.

Such repellants are considered most important in August and September, when the Culex pipiens mosquito, which carries the West Nile virus, is most active.

"Every retired gentleman in Toledo has a boat in the backyard that he bought 20 years ago and hasn't touched since," Mitchell said from his home in Ohio. "These things collect rainwater and become breeding grounds for mosquitoes."

Mitchell declined to offer an opinion on garlic oil.

The Boerner Botanical Gardens, in Hales Corners, Wis., uses garlic oil even though the place doesn't have a mosquito problem. "We use it to keep the deer from eating our roses," said Shirley Dommer, director of the gardens. "It works."

Joseph Sjostrom writes for the Chicago Tribune.

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