Westerly to conduct aerial spraying of larvicide in Chapman Swamp

Sun file photo

PROVIDENCE — The state departments of Environmental Management and Health have announced that an aerial larvicide application will be conducted Thursday, Sept. 5, in Chapman Swamp in Westerly.

Two Eastern Equine Encephalitis mosquito detections and one transmission in a horse have occurred in Westerly. Applications of the larvicide will also be conducted in the South Branch area of the Pawtuxet River in West Warwick, in the vicinity of the state’s first human case of EEE; and in the Valley Marsh area surrounded by Lincoln, Cumberland, and Central Falls.

 The flights will be done weather permitting; the wind must be calm.

Officials said that the latest trapping detections of mosquito disease reaffirm the need for increased use of pesticides, and the state intends to kill both larval and adult mosquitoes. “Larviciding” refers to the application of a product that kills mosquito larvae before they mature into adults. The aerial application to be done Thursday affects all mosquito species and reduces risks for both EEE and West Nile Virusinfections.

 The product, Bti, is a naturally-occurring bacterium. Officials said that the EPA has concluded that Bti does not pose a risk to humans. Bags of Bti will be loaded onto a helicopter, which will disperse the granules/pellets  in swamps and other breeding habitats. Bti produces toxins that specifically affect the larvae of mosquitoes, black flies and fungus gnats. These toxins do not affect other types of insects including honeybees. It is approved for pest control in organic farming operations.

Since the last round of trapping on Aug. 26, DEM has added traps in West Warwick; Burrillville, North Smithfield, and Cumberland, which border several Worcester County communities that Massachusetts public health officials have identified as areas of high risk; and West Greenwich, near the state line with southeastern Connecticut where there have been numerous EEE detections in mosquitoes and two cases of EEE virus infection reported in horses.

With the input of public health experts at the health department and entomology experts at the University of Rhode Island, DEM is placing nearly 40 mosquito traps in 23 communities across the state.

The state will release a spraying schedule and additional information before conducting any “adulticiding” flights  to control adult mosquitoes to combat an outbreak of mosquito-borne disease. It is often applied by aircraft through sprayers, which dispense aerosol droplets that stay aloft and kill flying mosquitoes on contact.

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