Suffolk authorities will be spraying pesticides across portions of the county Wednesday and Thursday to control the mosquito population, officials said.

The Department of Public Works’ aerial and ground spraying effort was scheduled to begin Tuesday evening on Fire Island with a later spraying set for East Patchogue, Bellport, North Bellport and Brookhaven hamlet.

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On Wednesday, officials said West Gilgo Beach, Gilgo Beach, Oak Beach, and Captree Island will be sprayed from 5:30 a.m. to 8 a.m.; Seaview, Ocean Beach and Ocean Bay Park on Fire Island from 6 p.m. to 10 p.m.; and Shirley, Mastic and Mastic Beach from 7 p.m. to 11:30 p.m.

On Thursday, officials said communities in Islip, East Islip and Great River, including streets east of Orowoc Creek in Islip to Connetquot River in Great River and south of the Long Island Rail Road tracks to the Great South Bay, are scheduled for spraying from 7 to 11:30 p.m.

Officials advise children and pregnant women to avoid the spray areas and remain inside until about 30 minutes after the spraying is completed. They also advise residents to close windows and doors and the vents of window air-conditioning units.

The spraying is being prompted by concerns over the transmission of the West Nile virus from mosquitoes to people. This year, there is also a concern about the Zika virus, which can be transmitted by a certain type of mosquito that has not been found on Long Island.