The pesticide applications are designed to control mosquitoes, which can spread the West Nile virus through bites.
Suffolk County is reporting 199 mosquito samples and 37 birds testing positive for the virus this year. Two human cases have been confirmed in the county, with both people having recovered.
Chances of experiencing medical problems because of the pesticide applications are low, health officials said, but residents may want to avoid exposure, with children and pregnant women especially advised to stay indoors during the treatment and for 30 minutes after the spraying.
For more information, call the county's spray hotline at 631-852-4939, or see www.co.suffolk.ny.us online.