The state's public health pest management program decides where to spray based on mosquito counts and the population of people living in an area. Spraying is done in areas where sample counts exceeded 25 mosquitoes per minute on test subjects, and where population densities exceed 151 people per square mile.
Spraying is not done in areas with low mosquito counts or low population densities. Other areas not sprayed include state parks, federal lands, wildlife and nature preserves, and lakes, sounds and other waters (excluding floodwaters).
"We are trying to benefit the most people in a timely manner," said Dr. Nolan Newton, chief of the public health pest management section. "We also are trying to minimize potential environmental impacts from spraying by avoiding sensitive areas and locations with few mosquitoes or people."
Once an area is scheduled for spraying, pilots can fly only during specified time periods and weather conditions. Spraying must be done during daylight hours, but not between 10 a.m. and 3 p.m., when bees are active. Spraying also cannot be done when: temperatures fall below 55 degrees; winds exceed 17 miles per hour; and fog or rain is present.
The insecticides that will be used to kill the adult mosquitoes are malathion and pyrethroids. Although the chemicals pose little risk to humans or animals, health officials are advising residents to stay indoors with windows and doors closed for 30 minutes after the airplane passes as a safeguard. Residents will be able to see and hear the planes as they pass overhead.
"Following Hurricane Fran, we did a risk assessment on the various pesticides used to fight mosquitoes," said Dr. Luanne Williams, a state toxicologist. "Our risk assessment shows that the malathion and pyrethroids pose little risk to humans, but do pose a risk to fish, bees and aquatic animals. As with all pesticides, you should take care to reduce or eliminate any exposure that is not absolutely necessary."
The risk to bees, fish and aquatic animals will be minimized. The planes will fly in the early morning and early evening to avoid bees, and will minimize releases of insecticides over water.
An EPA study found that malathion did not pose any significant threat to public health. In fact, officials with the state Division of Environmental Health's pest control program say that malathion is one of the most widely used home and garden pesticides. "Malathion is less toxic than many other chemical insect sprays commonly used by homeowners," said Newton.
Pest management staff use about 40 sentinel chicken flocks scattered across the coastal plain to monitor for viruses like Eastern Equine Encephalitis and St. Louis Encephalitis. Testing for SLE will also reveal West Nile Virus, which is blamed for several recent deaths in New York state. Pest management staff draws blood from these chickens and tests it for viruses. "Because the viruses are transmitted from birds to mosquitoes and then to humans, we can get a good early warning when there is a risk for mosquito-borne encephalitis," said Newton. "Our testing this year has found no St. Louis Encephalitis. We have found five chickens in Bladen County and one in Hyde infected with Eastern Equine Encephalitis, but this was found before the storm and is normal activity for this time of year.
"We don't have a disease problem with mosquitoes right now," he added. "But, we do have a big nuisance. The recent heavy rains is causing increased numbers of mosquitoes and that's adding to the existing stress of the residents and interfering with recovery efforts."
The spraying will only reduce current mosquito problems. It will not prevent future infestations of mosquitoes. People can help reduce mosquito problems by eliminating outdoor containers that hold water, such as cans, jars, buckets and old tires.
To protect themselves from mosquitoes, residents can use repellants, wear long pants and long-sleeved shirts. Be sure to follow directions carefully when using repellants.
Updates on mosquito spraying can be obtained at the following web site: www.deh.enr.state.nc.us/Floyd/floyd.htm.
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