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Town of Westerly to Conduct Aerial Treatment of Mosquito Larvicide on Chapman Swamp April 25

PROVIDENCE, RI The Department of Environmental Management (DEM) today announced that the Town of Westerly will conduct an aerial application of mosquito larvicide across 500 acres of Chapman Swamp and nearby swamplands tomorrow, Tuesday, April 25, weather permitting. The application, which consists of pellets that kill mosquito larvae being dropped by a helicopter, will take place between 8 AM and 2 PM. In the event of inclement weather, a rain date will be announced.

Bti, a naturally occurring bacterium applied in granular form to control mosquito breeding in swamps and other breeding habitats, is the treatment that will be applied. It is applied to standing water where developing larvae are found. It is an environmentally friendly product whose toxins specifically affect the larvae of only mosquitoes, black flies, and fungus gnats and do not pose a risk to human health. Larviciding is recommended as part of the state's action plan to control 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 of Westerly, however, 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, 2020, and 2022. 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 parts the swamp and swampland near Hespar Drive.

For mosquito prevention tips, visit the Rhode Island Department of Health's website.

For more information on DEM programs and services, click here. Follow DEM on Facebook, Twitter (@RhodeIslandDEM), or Instagram (@RhodeIsland.DEM).

Related links

  • Department or agency: Department of Environmental Management
  • Online: http://www.dem.ri.gov/
  • Release date: 04-24-2023

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