How Does Mosquito Spraying in Wayland Work?

The Wayland Board of Health announced in May its plans to expand the town's mosquito control efforts beyond treating for larvae in wetlands to spraying for adult mosquitoes.

A Board of Health public hearing on Monday, May 20 brought East Middlesex Mosquito Control Project Superintendent David Henley to town to answer questions and explain the program. (The video from that hearing is available via WayCam)

Still, questions seem to persist, so Patch reached out to Henley for some additional clarification and to specifically ask the questions we've received from readers.

When will the spraying occur?

First of all, Henley explained, Wayland has laid the groundwork for spraying to take place. But it won't happen if it isn't needed.

"It's going to be something that is going to be put into effect later this summer if there's a risk of West Nile or EEE [Eastern Equine Encephalitis]," Henley said, continuing to warn that "The rains that we just had and the rains that we're about to have are actually going to produce a very large mosquito population in late June and that will carry over into early July."

Henley explained that the Wayland Board of Health wanted to have the necessary discussions well in advance of the peak season so that all the logistics, including an opt-out option, would be in place.

"Once it's necessary, maybe it's too late to talk," Henley said. "We [EMMCP] need a little bit of advanced time so that we can set up information to tell us where the people who have opted out live."

What does it mean to "opt out"?

Henley explained that EMMCP honors the requests of individuals who opt out of the spraying, which means that their immediate neighbors will likely also not be sprayed.

The EMMCP considers a number of factors when it comes to the areas it sprays. Henley said the organization will look at any opt-out requests in an area or neighborhood and make individual decisions about how best to treat the area while respecting the opt-out request or requests. (For more information on opting out, see last week's You Ask, Patch Answers: "How Do I Exclude My Property from Mosquito Spraying?

The deadline to opt out of the spraying in Wayland in July 1.

Henley said that historically the EMMCP has had anywhere from 5-20 property owners opt out of the spraying in any given town. EMMCP has been conducting adult mosquito control as needed in Sudbury, Weston and Framingham for many years, he said.

Henley explained that the spraying is most effective in areas where the streets are close together and obstructions are limited. For wide, isolated streets (he used Lincoln Road in north Wayland as an example), the effectiveness is limited.

How does the spraying work?

Mosquitos are most active after dusk, Henley said, so spraying takes place after dark.

He explained that each spray truck is staffed by two individuals -- one who operates the truck and watches for people who are out in the yards or streets and one who simply watches for people who are outside. If a person is spotted in the treatment area, spraying stops, Henley said.

"Truck spraying is just meant to go with the other types of control programs that are available," Henley said, adding that the most effective control would occur though aerial spraying, but that poses too many environmental and political issues, he said, to be an option. "So you use a series of less effective controls."

The next best option is to use BTI to control the mosquito larvae population in wetlands, which has taken place in Wayland for years, but EEMCP isn't permitted to use BTI in the Great Meadows Wildlife Refuge.

The Wayland Board of Health said in its original press release about the adult mosquito spraying that the restrictions in Great Meadows as well as the multiple cases of West Nile and EEE last year led to the decision to pursue adult mosquito control this year.

Is it safe?

Henley said that the state has been using the same chemicals for several years in southeastern Massachusetts and has been monitoring the effects on people and the environment.

"Each time, they've done extensive studies of impacts, and they really haven't found much of an impact," Henley said, explaining that neither people nor aquatic insects and other wildlife seem to be affected. "It's to the point where Fisheries and Wildlife doesn't really want to keep checking because they don't think they're going to find things.

"The toxicity of the material is actually very low, so it's not like people ever feel anything from the spraying," Henley said. "The small nighttime flying insects are the target."

Information about the pesticides used by EMMCP is available on its website.