The city's Health Department is taking action to lower the threat of mosquitoes and the West Nile virus in the borough.
Helicopters will be spraying bug-prone areas with larvicide, a pesticide that is not toxic to humans, through Friday.
Marshy land in and around Pelham Bay Park is being targeted, along with parts of Queens and Staten Island.
Health officials say the mosquito-borne West Nile virus has not been detected anywhere in New York City this season, but there were about 30 cases last year, including at least six in the Bronx.