Summer mosquito control starts in your own back yard

Published July 14, 2007

Recently, I made the mistake of trying to sit on my deck at twilight, my favorite time of day during the summer in Florida. It's when the sky turns lavender and peach and there's a promise - albeit a faint one - of the coolness of the night ahead.

Five minutes later, I gave up and went inside after what felt like a stealth attack by a swarm of particularly nasty mosquitoes that managed to leave a constellation of tiny welts on my ankles.

It's that time of year in the sub-tropics and the shelves of the drugstores and hardware stores burgeon with products to help eradicate pests and make outdoor living bearable again.

Whether you like to entertain or prefer to unwind solo on your patio, deck or balcony, there are ways to reduce mosquitoes, even during the rainy season.

But before you start stocking up on the citronella candles ever noticed how they work for some people but not others?, here's some advice from Marina D'Abreau, Florida Yards and Neighborhoods Coordinator with the Hillsborough County Cooperative Extension Service.

"The most obvious advice is that you don't want to have any sources of standing water -containers, pots or rain barrels (without covers)," she says.

Ponds, birdhouses and birdbaths are other breeding grounds for mosquitoes, as well as less obvious places where water might collect like bromeliads, which tend to hold water, especially during rainy season.

One option, she says, is to sprinkle BT granules (bacillus thuringiensus) into culprit areas where water tends to collect. This naturally occurring bacteria, developed as a microbial insecticide, was discovered in 1911 but not made widely available until the mid 20th century. It kills larvae when mosquitoes ingest it, but doesn't hurt wildlife.

"It's a very environmentally friendly approach to mosquito control," D'Abreau says.

She also suggests looking for areas in your yard that don't readily drain within 48 hours of a heavy rain.

"You should amend the area in some way by bringing in fill or putting in a French drain," she adds.

Another option for poor drainage areas is to plant a rain garden (use plants typically found around ponds like ornamental grasses) within the existing depression. It will cut down on erosion, reduce standing water and mosquito breeding, she says.

In the fight against patio/deck mosquitoes this summer, "your best bet is to get rid of as many potential (standing water) areas in your yard" as possible, she says.

Decks are a particularly rich source for mosquito breeding because the areas underneath tend to remain soggy long after a heavy rain.

"Mosquitoes prefer to be in dark dampness," says Ken Jones, a horticulturist with the Pinellas County Extension Service. "The dampness results from rain and dew accumulating. It's the last place it evaporates from because the underside of a deck is out of the sun."

People with raised decks might consider using a portable fan to air out the area underneath a few days after a soaking rain after the upper surface is completely dry.

As for burning citronella candles, well, you might have a bit of luck there: "The volatile oil in the citronella plant acts as a natural repellent," Jones says.

Just don't expect the candles to completely fix the problem.

"They're not going to get rid of mosquitoes completely - they're effective in small areas."

Your absolute best armor in the war against mosquitoes is to use repellent on your body.

Says D'Abreau: "Look for the kind that contains DEET."

What about the plethora of mosquito control devices and services on the market for homeowners? Don't invest in an ultrasonic device or bug zapper before you check out advice and research from the University of Florida at the Web site: http://edis.ifas.ufl.edu/TOPIC_Mosquito_Control

The site explains the difference between mosquito control and mosquito-borne disease prevention, a distinction most homeowners aren't aware of.

Controlling mosquitoes means reducing the population and thereby the number of bites in a designated area. Protecting yourself from mosquito-borne disease is different; it means protecting yourself from any mosquito bite.

As for those widely touted ultrasonic devices that act like an invisible fence for mosquitoes, Jones remains skeptical.

"They're a nice gimmick," he says, "but there's been a lot of good research that shows they don't affect the mosquito population that much."

Elizabeth Bettendorf can be reached at ebettendorf@hotmail.com.