To control mosquitoes, the Health Department will apply larvicide by helicopter to marsh and other non-residential areas of Staten Island, the Bronx and Queens next week. The spraying is scheduled for Tuesday, August 25, through Thursday, August 27, between the hours of 6:00 A.M. and 7:00 P.M. In case of bad weather, application will be delayed until the next day during the same hours. While three days are allotted for this activity, the application may be completed in less time.