[Mosquito Control] Rethinking Mosquito Control

Green pools are common in neighborhoods with foreclosed homes, and should be drained or treated. (Photo by M. Merchant)

Editor’s Note: The following article appeared on Mike Merchant’s blog, “Insects in the City,” which can be found at http://insectsinthecity.blogspot.com. The blog offers readers news and commentary about the urban pest management industry and is excerpted here with permission of the author.
 

After last summer’s West Nile virus outbreaks in north Texas and other parts of the country there is a heightened awareness of mosquitoes and mosquito issues.

Every pest management professional, especially anyone involved with residential pest control, should think of mosquitoes as an opportunity to provide another valuable customer pest control service.

In my experience, few people imagine that they might be the culprit when it comes to breeding mosquitoes. Most folks believe that mosquitoes come from someone else’s property — especially the creek across the street, or the neighbor’s fish pond.

While this might be true, especially in the case of an abandoned pool or marshy area, we are often our own worst enemy. Most creeks, ponds and lakes are not major sources of disease-carrying mosquitoes. Any body of water with fish, or with running water that is not stagnant, is not likely to be an important breeding site for the worst mosquito species — most of which are “container breeders.” Rather, small containers or human structures that collect dust and debris along with water that sits for more than a couple of weeks, are the most likely source for our worst disease transmitting mosquitoes like the urban-dwelling Aedes and Culex species.

A few years ago, Dallas County did an evaluation on the properties of citizens who reported severe mosquito problems in their backyards. They found that 25% of citizens who complained about mosquitoes were breeding mosquitoes in containers found in their own yards.

Problem Areas. As a PMP you approach every property with trained eyes to see pests and to see conditions that are conducive to pest infestation. This skill can serve you well when inspecting a backyard for mosquitoes, and provide value-added to any pest control visit. Here are some of the common problem areas to be alert for in residential yards:

A simple bucket with leaves and compost becomes a mosquito breeding site after a rain. (Photo by M. Merchant, in his own backyard — oops!)

Water- and leaf-filled bird baths. Bird baths should be emptied or cleaned weekly to minimize risk of mosquito breeding.

Gutters that fail to drain properly. This can be difficult to see, but your extension mirror can help. Check gutters, especially after a rain, to make sure they are draining properly. Leaves and dirt that build up in gutters provide the organic matter, all they need is water to make a mosquito-breeding spot.

Tires. Rubber automobile tires, it seems, are designed to hold water. They are one of the worst sources of mosquito breeding in some areas.

Buckets, plant pots and wheelbarrows without drain holes. These items should be inverted or hung to ensure that water is not held.

Landscape and gutter drain lines that catch and hold water. Poor installation of underground drain pipes allow water to stand. Mosquitoes are adept at finding their way in and out of underground holes that we may not notice. All underground drain lines should be fitted with a pop-up drain emitter that opens only when water is flowing.

Water catch basins/septic tanks. Catch basins in French drains and municipal storm sewers are designed to keep debris from clogging drain pipes. But these same boxes can catch and hold water for extended times. Flush out catchment basins or apply a larvicide like Bacillus thuringiensis or methoprene. Poorly closed or maintained septic systems can provide many breeding sites for Culex mosquitoes.

Uncapped steel fence posts are often overlooked, but may hold water for long times after a heavy rain. Point out fence posts without covers and explain how any container that holds water can breed mosquitoes.

Plastic or canvas covers on boats or trailers. Tarps or plastic sheets used to cover vehicles or boats can easily hold water for a week or more. Boat covers should be pulled taught to force water to drain.

Rain barrels and cisterns. Many homeowners have installed cisterns and rain barrels to capture and store rain water. While most commercial rain storage systems come with drains to keep mosquitoes out, screening on intakes and overflow plumbing can become damaged, and needs regular inspection.

Unmaintained swimming pools. So called, “green pools” are unchlorinated pools that can become breeding sites for large numbers of mosquitoes. If you notice such a pool and the homeowner is absent or unwilling to respond to complaints, these sites should be reported to the local health department as a public health threat.

Final Thoughts. Let’s all do our part to keep our communities safer and mosquito free. Let your customers know when they have a dangerous situation. Chances are that they will thank you for it. For more information on mosquitoes in backyards, see the Mosquito Safari website (http://mosquitosafari.tamu.edu/index.swf).

The author has been an entomology specialist for Texas AgriLife Extension since 1989. Readers can contact him vie e-mail at mmerchant@giemedia.com.