Controlling mosquitoes around your home and garden

Mosquitoes have buzzed around our planet for countless millions of years, long before the emergence of man and insect repellant. They have spread malaria across the globe, helped decimate isolated villages and have spoiled innumerable picnics and walks on the beach. At great cost — and to no avail — we have fought them with DDT, incense coils and backyard foggers.

Nowadays, mosquitoes are very much in the news. The reported incidence of malaria has quadrupled worldwide, while here in the U.S., the spread of West Nile Virus has mobilized public health officials and terrified residents. There even have been several futile efforts to use pesticide sprays to control adult mosquitoes.

Mosquitoes are bad news, but it is time for some perspective. The risk of contracting West Nile Virus is inconsequential compared to the life-threatening risks associated with driving a car, smoking, food-borne illness and obesity.

The simple fact is that mosquitoes are a part of our natural world, like it or not. Fortunately, in our area, most do not carry infectious diseases. The only species of mosquito in the wild that has been found to carry West Nile Virus, Culex pipiens, is not active during the day. Also, this species has a very limited flight range, measured in hundreds of yards rather than miles.

If this common house mosquito is around your home, chances are that either you or your neighbors are providing the necessary habitat for the insects to breed. Eliminating habitat is the key to controlling mosquitoes. If you do not provide an area for adults to deposit eggs, or do clean out potential breeding area periodically, the life cycle of the insect will be disrupted and no new mosquitoes will emerge.

Mosquitoes need water, primarily still or stagnant water rich in organic matter upon which mosquito larvae can feed. Among the most common locations for this habitat are the saucers gardeners frequently place under potted plants, especially on decks and patios. One option is to remove the saucers altogether, or at least dump them every couple of days.

For balcony and rooftop gardeners, self-watering containers have become increasingly popular. However, the reservoir beneath the container can breed thousands of larvae. As most of these containers cannot be emptied, an alternative is to tape over the access slot or hole used for filling the pot. This will keep out adult mosquitoes and trap existing larvae inside. Any other containers around the garden, such as watering cans, vases, buckets and wheelbarrows, also should be emptied and either stored indoors when not in use or turned upside down.

For gardeners who like to root cuttings in jars and bottles outdoors, emptying the container and refilling it with fresh water every couple of days is advisable. Fresh water will encourage rooting and help eliminate mosquito larvae.

Dripping outdoor faucets should be fixed immediately, both to conserve water and prevent puddles from developing and providing habitat. Also check on rain gutters and downspout areas, especially if you use corrugated plastic pipe to divert water across your lawn. Cover rain barrels with a fine mesh, such as window screening, to keep out mosquitoes. And make sure air conditioning units are not creating puddles as they drain condensed moisture.

Some yards have natural depressions that can form impromptu ponds or bogs during rainy weather. Correct such areas either through grading, which can be expensive, or by creating natural garden areas with moisture-loving plants that can take up excess water and convert it to flowers and foliage.

Ornamental ponds have grown in popularity, thanks to easily available and inexpensive pond liners and supplies. If the pond is stocked with fish, any eggs or larvae will be consumed readily. Aerate, filter or add fish to ponds merely hosting water lilies or other plants, or nothing at all. Even a simple dollar's worth of goldfish will control mosquito populations. Maintain ponds without electrical access with any one of several models of solar-powered pumps and filters.

One unfortunate side-effect of public concern with West Nile Virus is that people are dumping or removing birdbaths. Empty and replace the water in birdbaths every two to four days, both to prevent the spread of avian diseases and to eliminate breeding areas. But removing birdbaths altogether can actually prove a hardship for smaller songbirds, like goldfinches, who easily overheat in summer conditions and require safe havens to cool off, especially as natural water bodies are becoming more scarce.

In addition to typical garden areas, address a number of other mosquito breeding locations. A basic rule of thumb is that if it can hold water, it can breed mosquitoes. Tarps draped over woodpiles or lawnmowers can provide depressions that quickly become mosquito pools. Empty them immediately and rearrange the tarp so that it sheds rainwater. Tarps or covers over pools may keep out leaves and debris, but rainwater settling atop the tarp becomes prime mosquito habitat. A pump may be necessary to drain pool covers.

Wading pools, however small, can invite mosquito activity. Empty them after use and store them on their side, or deflate them. Simply turning the pool upside down will only provide a smaller catch basin for rainwater.

Watch out for water captured in uncovered trash cans or upturned trash can lids. Consider drilling holes to facilitate drainage. Recycling containers left outdoors also can trap water, as can bottles or cans left in the blue bin for more than four days. Again, consider drilling holes in the corners and handles of bins to ensure proper drainage at all times.

Finally, after eliminating or addressing the standing water on your property, think about becoming proactive. After all, getting rid of mosquitoes in your yard does not stop them from breeding in your neighbor's yard. Spread the word to the folks next door and speak up at community association meetings. Working together, your neighborhood should set about identifying potential habitat sites, one backyard at a time. Eventually, you will accomplish what no amount of pesticide ever achieved as you rid your immediate community of mosquitoes naturally and safely.

– Joseph M. Keyser

Click on this image to link to DEP's award-winning Mosquito and West Nile Virus Information Pages

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