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The original item was published from 4/27/2021 2:13:35 PM to 5/8/2021 12:00:04 AM.

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Town News Flash

Posted on: April 27, 2021

[ARCHIVED] Mosquito Larvicide Spraying 5/4/2021

The Rhode Island Department of Environmental Management (DEM) today announced the Town of Westerly will begin aerial application of mosquito larvicide across 500 acres of Chapman Swamp and nearby swamplands by helicopter on Tuesday, May 4, weather permitting.  Spraying will take place between 8:00 a.m. – 2:00 p.m. In the event of inclement weather, a rain date will occur on the first day after May 4 when weather permits.

Bti, a naturally-occurring bacterium applied in granular form to control mosquito breeding in swamps and other breeding habitats, will be applied.  It is an environmentally friendly product and does not pose a risk to human health.  Larviciding is recommended as part of the state’s action plan for West Nile Virus and Eastern Equine Encephalitis (EEE) and considered an effective strategy to reduce mosquito populations and related disease risk.  

In most communities, the state recommends applying larvicide by hand to roadside catch basins.  In the Chapman Swamp area, aerial application is recommended given the area’s remote location and large footprint. Mosquitoes carrying the EEE virus were found in Chapman Swamp in 1996, 2003, 2019 and 2020.  Since 1997, the Town has applied Bti annually to help control mosquito breeding.  Additional dates for spraying may be scheduled by the Town; the targeted areas include portions of Chapman Swamp and swampland adjacent to Hespar Drive.

For mosquito prevention tips, visit the Rhode Island Department of Health’s website at For information about DEM divisions and programs, visit  Follow us on Facebook at or on Twitter (@RhodeIslandDEM) for timely updates.

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