Four critical risk aread of Rhode Island will see aerial mosquito treatments on Sunday

Weather permitting, aerial spraying to reduce adult mosquitoes is anticipated to start at dusk on Sunday, September 8, in four critical risk areas of Rhode Island.

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The Department of Environmental Management (DEM) and the Rhode Island Department of Health (RIDOH) today announced that the state will begin aerial mosquito treatments starting at dusk on Sunday, September 8, weather permitting, with the possibility of a second night of spraying if needed. All spraying will occur in the evening and overnight hours.

A press release from RIDEM says the application will treat the four areas that the state Mosquito-Borne Disease Advisory Group (MBDAG) has assessed to be at critical risk for the Eastern Equine Encephalitis (EEE) virus.

Critical risk areas that will be sprayed include parts of communities in northern Rhode Island bordering the Massachusetts towns of Uxbridge, Douglas, and Mendon, where EEE has recently been confirmed in three horses. Another area includes Central Falls, where EEE was detected in two mosquitoes and announced August 15. Another spraying zone includes parts of Westerly, where DEM has confirmed two positive EEE detections in mosquitoes as well as a case being transmitted to a horse. The fourth zone will cover West Warwick, which is the location of the state’s first human case of EEE, and parts of perimeter communities.

Yesterday, the state conducted “larviciding” flights – through which a helicopter dispersed pellets of pesticide to kill mosquito larvae – in swampy areas near Central Falls, in West Warwick, and in Westerly.

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The determination of critical risk was made based on results of mosquito samples in Rhode Island, Massachusetts, and Connecticut and cases of EEE in mammals in Rhode Island. There has been one human case of EEE in Rhode Island this year and one horse tested positive. Generally, spraying will occur in four-mile radiuses around positive samples or cases. Because the aim of spraying is to protect humans from EEE infection, some areas will be excluded, including open bodies of water (including drinking water reservoirs), certain coastal areas, and natural areas that are not densely populated. Organic farms will also be excluded.

The ability to spray effectively depends on the weather. With the remnants of Hurricane Dorian tracking northward, the schedule may change. The forecast is predicting more rain tonight with showers tomorrow and windy conditions. Calmer conditions are needed to conduct aerial spraying.

EEE is a rare but serious and potentially fatal disease that can affect people of all ages. RIDOH confirmed the state’s first human case of EEE – in a person over the age of 50 from West Warwick – on August 30. Two mosquito detections of EEE have occurred in Central Falls and two have occurred in Westerly. The state’s transmission in a horse, announced August 29 by DEM, also originated in Westerly. In addition, several EEE cases and positive mosquitoes have been detected just across Rhode Island’s northern and western borders.

“This is a difficult situation, and DEM has collaborated with our colleagues in state government and academia to effectively address it,” said DEM Director Janet Coit in a press release. “In addition to aerial spraying in critical risk areas, we have dispersed larvicide, increased trapping, and partnered with RIDOH to amplify the message of personal precaution.”

“Although spraying will take place in a few select sites in Rhode Island, people in these communities and throughout the state should continue to take precautions to prevent mosquito bites,” said RIDOH Deputy Director Ana Novais in a press release. “Your first line of protection remains limiting time outdoors at sunrise and sundown, wearing long-sleeved shirts and long pants when outside, and using EPA-approved bug spray that has DEET.”

Following up on the larvicide treatments yesterday, the aerial spraying currently scheduled for Sunday will target adult mosquitoes in critical risk areas to further combat the outbreak of mosquito-borne disease.

The product used in this application is called Anvil 10+10. It has been used extensively in both ground-level and aerial spraying and has proven to be extremely effective in killing mosquitoes worldwide for more than 20 years. Massachusetts officials used the same product in recent aerial spraying in Bristol, Plymouth, Worcester, and other counties. Anvil is registered by the US Environmental Protection Agency (EPA) and in Rhode Island and Massachusetts for this use. This product is being used at very low concentrations. No adverse health risks are expected with its use for mosquito control. However, if people want to limit their exposure to this pesticide, they can avoid being outdoors while spraying is occurring and can keep their windows closed. More information health and spraying is available online.

Alterative active ingredients in bug spray are picaridin, IR3535; and oil of lemon eucalyptus or paramenthane. Always read the label and follow all directions and precautions. Do not use bug spray with DEET on infants under two months of age. Children should be careful not to rub their eyes after bug spray has been applied on their skin.

On Monday of last week, RIDOH recommended to schools and municipal leaders that games, practices, and other outdoor activities scheduled to occur during early morning or dusk hours be rescheduled to earlier in the afternoon or relocated to an indoor venue. The “smart scheduling” of events is intended to help minimize the risk of mosquito bites for players, coaches, and spectators. RIDOH recommends that smart scheduling stay in effect for the remainder of the mosquito season, which typically ends in mid-October (after the first hard frost).

For more information about DEM divisions and programs, visit Visit for additional mosquito prevention tips, videos, and local data.