Avoid spraying, prevent mosquito reproduction

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If they can’t breed, you don’t need to worry about using pesticides

By Nathaniel Smith, Columnist, The Times

NSmithColLogoI recently noticed a newspaper article that is very misleading about the costs and benefits of spraying to control mosquitoes.

The story was much too casual about the use of toxic chemicals in residential properties. It brought out that the insecticides known as pyrethroids, widely used to kill insects, are “EPA approved” but that means, unfortunately, very little. The EPA itself says, among other cautions, that “pyrethroids are toxic to fish and to bees,” and the manufacturers’ instructions are full of warnings as well.

Dangers of spraying pyrethroids

The 256-page Pennsylvania Pesticide Applicator Certification Core Manual points out that, for humans, “Symptoms associated with synthetic pyrethroid insecticides include nausea, dizziness, weakness, nervousness, eye, and skin irritation.”

Pesticide drift is another problem: air-borne spray will not stay within a property line. If I spray my yard with an insecticide, my neighbors may not welcome it drifting onto their organic gardens, their children, and their cats (pyrethroids are toxic to cats),

How do I and the pesticide company warn everyone who could be downwind at the particular time of application? And what about wind-borne residue (which takes about 24 hours to break down) that settles onto, say, children’s play equipment or cat-frequented areas?

And how about any neighbors who are medically hypersensitive to all chemical exposure? Do we expect them to move away during and after pesticide applications?

Rain-carried runoff of pesticide residues, ultimately into wetlands, streams and rivers, is also an issue: “Pyrethroids are highly toxic to aquatic organisms” (EPA).

Limitations of spraying

The EPA Manual also brings up a serious long-range concern (similar to what happens when we overuse antibiotics): the more pesticides people apply, the more rapidly insects, especially the fast-reproducing mosquitoes, will develop immunity. Then, ironically, the pesticides will still be killing not mosquitoes but beneficial insects, like dragonflies (which actually eat mosquitoes), butterflies, and the bees that are vital to flower pollination and agriculture.

Application can’t be done at just any time.  The temperature should be above 50 degrees, wind speed between 1 and 10 mph, and time of day early morning or evening, when mosquitoes prefer to venture forth.

Spraying kills only about 80% of mosquitoes in the air and does not affect eggs and larvae, which will become adults in a few days. And mosquitoes are good flyers; even if we could kill off all adults from our yard, their relatives would soon be back.

What can citizens do?

Mosquito control and public health hazards should be governed not by individuals making decisions on their own but by county health authorities, who have the professional background to know when the threat of an insect-spread disease outweighs the negative consequences of air-borne spraying.

This doesn’t mean that we citizens can’t do anything to help. In fact, only we can really solve the problem, by preventing mosquitoes from breeding on our properties.

As the weather warms up -meaning now- we need to eliminate (or regularly empty) all outdoor sources of standing water from our properties, such as bowls and pails, trash cans and overturned lids, birdbaths, wading pools, old tires, and saucers under potted plants. Eaves should be checked for leaves blocking drainage. Ponds should have larvae-eating fish in them or be treated with the readily available and totally safe biological larvicide Bti (AKA “mosquito dunks” and similar).

Any of us who insist on spraying our own properties should investigate natural, non-toxic sprays on the market.

Municipalities also need to treat storm water drains, which can be mosquito breeding grounds-ironically, more so in dry weather, when the water we can’t see under the streets is not flowing and is therefore congenial to larvae growth.

Mosquitoes are a nuisance but also, since they can carry disease, a public health problem, though here nothing (yet) like in some other parts of the world. We should all do our part to minimize mosquito breeding so that pesticide spraying becomes what it should be: the last resort.

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