The county's department of public works will apply the pesticide Anvil by ground spraying from 6:30 p.m. to 10:30 p.m., the county said in a release.
The county health department said that "health effects from spraying are quite low," but advised that common-sense steps should be taken to avoid exposure. Children and pregnant women, the release said, should "remain inside or avoid the area whenever spraying takes place and for about 30 minutes after spraying."
To keep the pesticide from getting indoors, health officials said, "Close windows and doors and close the vents of window air-conditioning units ... before spraying begins. Windows and air-conditioning vents can be reopened about 30 minutes after spraying."
Outdoors, pick homegrown fruits and vegetables, if possible, before spraying. Bring in laundry and all small toys indoors. If items are exposed to the pesticide, wash with soap and water.
Also, the release said, pet food and water dishes should be brought inside, and ornamental fish ponds should be covered during the spray period.
More information is at an information hotline, 631-852-4939, or at suffolkcountyny.gov/health.