A helicopter under contract with County Vector Control will be dropping pesticide granules on Wednesday over ponds in the San Diego River in Santee to control mosquitos.
The pesticide consists of corn cob or sand granules coated with naturally occurring bacteria that target mosquito larvae and prevent them from developing into biting adults.
Vector Control says the granules are not harmful to people, pets, plants or wildlife.
The aerial pesticide applications take place between April and October as part of a public health effort to control West Nile virus.
More information about the program is available on the Vector Control website at www.sdcounty.ca.gov/deh/aerials