Suffolk County schedules aerial mosquito larvicide treatments for July 21-24

Suffolk County scheduled aerial mosquito larvicide treatments for marshes in Riverhead, Flanders, Southampton and Southold from July 21 through July 24, using low-altitude helicopters and granular larvicide. The point is prevention: the county is targeting mosquitoes while they are still developing in water, before they become biting adults and, in some cases, before they can spread disease.

A county notice for the July 21-24 round listed a 7 a.m. to 6 p.m. application window. Residents near the affected wetlands can expect helicopter activity over marsh areas during those daylight hours, part of a broader county effort to suppress mosquito breeding in places that are difficult to reach from the ground.

Suffolk County Public Works said in a social media post that it was treating parts of some marshes by helicopter to control mosquito larvae. The method matters because marshes, wetlands and other standing-water sites can produce mosquitoes quickly after rain or prolonged heat, and aerial larviciding lets crews reach those breeding areas before the insects emerge and spread out into nearby neighborhoods, parks and outdoor gathering spaces.

The county has used the same basic approach in other summer notices, including a July 23-26 window that listed a 6 a.m. to 6 p.m. application period. Suffolk has also repeated marsh-treatment plans in prior summers, including in 2025 and 2016, showing that aerial larviciding is part of a standing mosquito-control program rather than a one-off response. That work sits within Suffolk’s formal Vector Control and wetlands management planning framework, which ties mosquito suppression to long-term management of the county’s marshes and shoreline habitat.