Residents opting out of mosquito spraying over pesticide concerns

Cattail mosquitos can transmit Eastern equine encephalitis and West Nile virus to humans. Both diseases can be fatal.
Pat Wellenbach/Associated Press/File 2010
Cattail mosquitos can transmit Eastern equine encephalitis and West Nile virus to humans. Both diseases can be fatal.

Hundreds of local property owners are expected to opt out of mosquito spraying this spring, leaving gaping holes in regional efforts to eradicate potentially lethal viruses carried by the pesky insects.

In late March, the Northeast Massachusetts Mosquito Control and Wetlands Management District is scheduled to begin spraying in the 32 cities and towns under its jurisdiction as part of a statewide initiative to keep the mosquito population down. But the efforts have been complicated — particularly by a backlash against the use of toxic pesticides — prompting entire towns to forgo seasonal spraying.

“There are some communities where it doesn’t even make sense to spray because so many residents have chosen not to participate,” said Bill Mehaffey Jr., superintendent of the Northeast mosquito district, which stretches from Revere to Amesbury. “And the reality is that the mosquitoes don’t know boundaries. Some of them can travel 25 miles looking for a blood meal.”


Cities and towns that join the mosquito control district pay the state up to $45,000 a year for spraying and other control measures. Homeowners who don’t want spraying on or near their property can opt out of the program but must do so by March 1. Unlike previous years, requests beyond that date won’t be accepted.

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Public health officials are concerned about mosquitoes because they are transmitters of both West Nile virus and Eastern equine encephalitis. Both diseases are potentially fatal to humans.

There were a record 33 human cases of West Nile virus in Massachusetts in 2012, and seven human cases of Eastern equine encephalitis, including two in Essex County that resulted in the deaths of people in Georgetown and Amesbury.

But in part because of aggressive spraying, the number of people diagnosed with West Nile virus dropped to eight in 2013 in Massachusetts, while there was only one confirmed case of EEE, which was not fatal, according to the state Department of Public Health.

More than 600 property owners opt out of the spraying every year, according to the Northeast district, citing the impact on honeybee hives and organic farms and fears about toxic pesticides.


Some towns, such as Marblehead and Swampscott, have banned the public use of chemical pesticides completely and rely on methods such as using traps to kill off mosquito larvae. In other towns, such as Boxford, large numbers of residents opting out of regional mosquito control have made neighborhood spraying largely ineffective, Mehaffey said.

“We’ve had virus issues in some of those towns and they’ve still opted not to spray,” he said. “I really don’t understand it.”

Mehaffey said despite the growing public concerns about the use of pesticides, the chemicals used in the spray have low toxicity and have been tested and approved by several state agencies as safe for use around humans and household pets.

“We can’t just use anything we want. We’re required to use products that the state approves,” he said. “There’s a lot of misconceptions by the public about what we are spraying. Some people think we’re still using DDT.”

Still, state health officials point out that contact with mosquito spray has been known to cause symptoms ranging from nausea, shortness of breath, and irritation of the eyes, ears, and throat. When the spraying is done, typically by truck or helicopter at night, local health officials warn residents to stay indoors, keep windows closed, turn off window fans, and keep pets inside.


Environmental groups such as the Washington D.C.-based Beyond Pesticides have been pushing state and local governments to reduce their reliance on what they call harmful chemicals while promoting more organic pest management alternatives.

“The pesticides most commonly used across the country are neurotoxic and have been linked to cancer and other illnesses,” the group states on its website. “People with compromised immune systems, chemically sensitive people, pregnant women, and children with respiratory problems, such as asthma, are particularly vulnerable to these pesticides and will suffer disproportionately from exposure.”

State health officials say mosquito-borne illnesses are becoming widespread and they say regional efforts to control the insects are vital to prevent outbreaks.

EEE is one of the most severe mosquito-transmitted diseases, with a 33 percent mortality rate and significant brain damage in most survivors, according to the Centers for Disease Control and Prevention. The illness poses the greatest risk to those under age 15 or over 50.

Mosquitoes also carry West Nile virus, which is less lethal but more common in parts of Southeastern Massachusetts, Greater Boston, northern Essex County, and in the Northampton area. The virus can cause illnesses ranging from a mild fever to more serious diseases like encephalitis or meningitis. The majority of people who are infected will have no symptoms, according to the CDC.

Christian M. Wade can be reached at Follow him on Twitter @cmwade1969.