To control mosquitoes, the Health Department will apply larvicide by helicopter to marsh and other nonresidential areas of Staten Island, the Bronx and Queens on Wednesday, July 28; Thursday, July 29; and Friday, July 30, between the hours of 6:00 A.M. and 7:00 P.M. weather permitting. 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.