Ground spraying to control adult mosquito populations on parts of Fire Island is scheduled for 6 to 10 p.m. Wednesday and Thursday, Suffolk County health officials said. Areas of South Shirley, Mastic Beach and Old Mastic are to be treated Thursday, officials said.

The pesticide applications are designed to control mosquitoes, which can spread the West Nile virus through bites.

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The Suffolk County Department of Health Services said ground spraying of the pesticide Anvil will be conducted Wednesday on all streets in Ocean Bay Park on Fire Island and Thursday on all streets in Fire Island Pines, Water Island, Atlantique and Summer Club on Fire Island.

Spraying of the pesticide Scourge is scheduled Thursday from 7:30 to 11:30 p.m. in areas of South Shirley, Mastic Beach and Old Mastic.

Chances of experiencing medical problems because of the 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.

More information is available through the Suffolk County Division of Vector Control at 631-852-4270, the county's spraying information hotline at 631-852-4939 or by checking the "vector control" section of the health department's website at