Mosquitoes Get A Whiff Of Doom

7/31/2006 Chicago Tribune

By Joseph Sjostrom

An Itasca nature center has been using a garlic-based repellent that its makers say kills the insects, helps the environment

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 with the threat of 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 Area Sanitary District in Ohio, 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 it 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, birds long thought to be voracious consumers of mosquitoes, showed their diet includes wasps, butterflies, stinkbugs and dragonflies, but no mosquitoes, Mitchell wrote.

Electrocutor 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 Mitchell noted that the fish don't eat one species of mosquito that spends its larval stage under water 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 many of their breeding pools as possible, treating breeding pools with chemicals or mosquito-eating fish, and using personal repellent products containing DEET.

Such repellents 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 back yard 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 it 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."