An East Middlesex mosquito truck sprays on Bedford's McIntosh Road, not far from a US wildlife refuge that bans the practice. (Jim Davis/Globe Staff) An East Middlesex mosquito truck sprays on Bedford's McIntosh Road, not far from a US wildlife refuge that bans the practice.

Even with bumper crop, mosquitoes are tough targets

Patchwork limits on spraying reflect split on risks, benefits

By James O’Brien
Globe Correspondent / August 27, 2009

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On a normal night, when staff from the East Middlesex Mosquito Control Project put out traps to catch and count mosquitoes, netting 200 of the insects means it’s time to spray. This mosquito season, however, has been anything but normal.

“We’re closer to 2,000 a night,’’ said the control project’s superintendent, David Henley, speaking of mosquito counts this month in Bedford, one of its 25 member communities.

Henley says two unusually rainy summers in a row have led to the burgeoning mosquito population.

Mosquito-control agents in other districts concur. But the explosion of late-summer broods represents only the most recent challenge in communities across Greater Boston at a time when the mosquito-borne West Nile virus has been detected in Waltham, Westborough and Westford.

The task of keeping mosquito counts down is hindered by variations in the way spraying is conducted from town to town, the officials say. In some communities, residents’ objections to pesticide use limits or rules out spraying. Also, spraying is not allowed in federally regulated conservation land, such as the expansive Great Meadows National Wildlife Refuge, where mosquitoes are viewed as part of a protected ecosystem that extends from Concord and Sudbury into a handful of area communities.

In Wayland, the state-run East Middlesex project is hired only to go after larvae and treat catch basins, where West Nile carriers like the culex mosquito thrive. The town does not allow Henley’s operation to spray airborne adult mosquitoes, leaving the insects to potentially fly untouched into neighboring municipalities.

“There’s a small section of Wayland that butts up against Framingham,’’ Henley said. “I’m sure there’s some impact.’’

Wayland’s Health Department director, Steve Calichman, said the choice to not implement adult spraying was decided years ago, well before his tenure. Residents reluctant to have pesticides sprayed in town tie his hands when it comes to additional treatments, he said.

“We try and reduce the number of larvae that are going to make it into the air,’’ Calichman said. “We’ve been doing the program in, I hate to say, a very conservative manner, but that’s the way it’s been.’’

Longtime Wayland resident Linda Segal, who sits on the board of directors of an antipollution organization, the Toxics Action Center in Boston, wrote to the town’s Board of Health several times around 2003 asking members not to implement spraying for adult mosquitoes. She was reacting, she said, to head off Henley’s presentations on additional spray options available to the town.

“I believe they’re acting properly in taking a precautionary, principled approach,’’ Segal said of the Board of Health and current spray limits. “The whole notion is to reduce unnecessary exposure to chemical pesticides, as much as possible.’’

As for the possible drift of mosquitoes from Wayland to Framingham, Segal said a regional mosquito-control approach might be preferable in stopping such transference, but she stood behind the right of each town to decide its own spraying limits.

Henley said he uses the pesticide sumithrin in quantities that fall within safety guidelines. East Middlesex sprays a mixture containing less than 1/1,000th of the amount scientists have found to be a baseline for possible toxic effects in test animals.

According to the US Environmental Protection Agency, sumithrin is in a class of pesticides shown not to pose “unreasonable risks to human health when applied according to the label.’’ The chemical is deemed safe for mammals and birds, in small amounts, but dangerous to fish and bees. The EPA restricts the use of chemicals near open water.

Segal takes little comfort from assertions that the pesticide concentrations are too small to harm humans.

“It’s hard to say there’s no physical impact on humans,’’ said Segal. “I worry about cumulative impacts. I take the position that I would rather wear long sleeves and not be sprayed.’’

Pesticide worries also limit mosquito control efforts in Carlisle.

Ernie Huber raises bees and wants the town to remain pesticide free.

“The town has, as a whole, fallen against it,’’ said Huber of opposition to mosquito-spraying proposals in recent years. “I do, too.’’

Even in diluted form, he said, pesticides could harm his bees, and he disputed that Carlisle’s no-spray policy has much affect on neighboring towns.

“I’m not even aware of people in our town being bitten more often by mosquitoes,’’ said Huber. “If we’re such a magnet, why don’t we have high numbers of West Nile virus?’’

Linda Fantasia, Carlisle’s health agent, said the most recent proposal for spraying came before the local Board of Health last winter. Residents raised enough questions that the board chose not to put the proposal before Town Meeting.

Henley said no-spray towns like Carlisle can have an impact on other communities. For example, he said, Bedford is close enough to get mosquitoes from Carlisle.

Additionally, Henley must deal with regulations pertaining to federal land, such as Great Meadows, which runs through Lincoln, Wayland, Carlisle, Bedford and Billerica as well as Concord and Sudbury.

Henley used to be able to treat mosquito larvae in the 3,800-acre refuge, but changes to pesticide rules stopped that practice around 2001. Now, all Henley can do is spray the adults that migrate into surrounding communities.

Libby Herland, who manages Great Meadows as part of the US Fish and Wildlife Service’s Eastern Massachusetts National Wildlife Refuge Complex, said her agency considers mosquitoes “a natural part of the ecosystem,’’ and should not to be sprayed, although a health emergency could override the policy.

Still, Herland voiced some sympathy for residents in the surrounding towns.

“I know folks are not happy about the fact that there are a lot of mosquitoes out there right now,’’ she said. “It’s a real issue, I’m not saying it’s not, and some of those mosquitoes may be coming from the refuge.’’

Meanwhile, in Medfield and Millis, the Norfolk County Mosquito Control Project’s director, John Smith, said landing counts - the number of mosquitoes touching down on a person - jumped this year from an average of five per minute to 20 per minute at locations along Route 109.

Smith deals with his own patchwork of spray and no-spray zones in his district. Some privately owned properties, including wetlands, are off-limits. As a result, some “residents are not getting the mosquito services they need,’’ Smith said.

In Harvard, which falls within the Central Massachusetts Mosquito Control Project, mosquito spraying was stopped in 1989, following a 171-13 vote at Town Meeting.

This summer in particular, Board of Health member Lorin Johnson said, he has noticed an increase in mosquito activity.

“My neighbors put the mosquito magnets out,’’ Johnson said. “Believe me, it has no effect whatsoever. They’re just overwhelmed.’’

Johnson is pushing for Harvard to take a fresh look at insect control. He hopes to bring the issue of both mosquitoes and ticks before the Board of Health in September.

“You pay taxes in a town and you expect a better scenario than what you get right now,’’ said Johnson. “We should not have to be battling ticks and mosquitoes the way we are, given the health risks.’’

But Selectwoman Lucy Wallace remembers the 1989 vote and knows how many people in Harvard feel about pesticide spraying.

“Enough people back then were concerned with spraying on wetlands and birds,’’ said Wallace. “The town has been historically pretty conservative about chemicals and their use in treating things.’’

The motion to stop the spraying cited a “lack of control’’ in the applications, according to Town Clerk Janet Vellante.

William Ashe is among the Harvard residents opposed to mosquito spraying, back then and now. He remembers the spray wafting through his windows, despite his no-spray requests.

“I could taste the pesticide, even though I said I didn’t want it,’’ he said.

Ashe is skeptical about the threat of mosquito-born illness. He said that concerns about mosquitoes straying from his town into neighboring communities that do spray do not justify exposing Harvard residents to pesticides.

“My concern then, and my concern now, is the spread of contaminants in our world,’’ Ashe said.

Tim Deschamps, executive director of the Central Massachusetts control project, said situations like Harvard’s no-spray rule have an effect on neighboring towns, like Lancaster.

Deschamps said a more comprehensive way of controlling the insects would be more effective.

“Mosquito control works better on a regional basis,’’ Deschamps said. “Because the town next door doesn’t have the program . . . residents on the outskirts don’t get their money’s worth.’’

The likelihood of that happening is slim at the moment, according to one health agent.

“We’re talking about New England, and we’re talking about Massachusetts, and home rule,’’ said Calichman, Wayland’s health director. “The political reality is I don’t think we’ll reach the ideal as far as the regional approach to mosquito control.’’