San Diego County's Mosquito Vector Control Program (VCP) applies mosquito larvicide via helicopter to mosquito breeding areas that cannot be treated by hand. These aerial applications occur every three to four weeks during the mosquito breeding season, generally April to October, or as needed.
The granular larvicides used by the Vector Control Program act specifically on mosquito larvae and will not harm people, pets, plants, or wildlife. The larvicide consists of granules containing Lysinibacillus (Bacillus) sphaericus, Bacillus thuringiensis israelensis, and/or Saccharopolyspora spinosa products. These naturally occurring bacteria target mosquito larvae and prevent them from developing into biting adults.
For more information: https://www.sandiegocounty.gov/fightthebite/