Aerial spraying of an insecticide to halt the growth of mosquitoes that can spread disease and bite viciously will take place in Palo Alto's Baylands Saturday, June 20, starting at 7:30 a.m., the Santa Clara County Vector Control District has announced.
The summer salt marsh mosquitoes are currently breeding in the area known as the Palo Alto flood basin, and "a significant number of salt marsh mosquitoes will become adults in a few days if left untreated," according to the district's June 19 press release.
The insect can fly up to 30 miles from its breeding grounds and spread the western equine encephalitis virus.
The spray will consist of a naturally occurring soil bacterium called "Bti," which activates when consumed by mosquito larvae, and methoprene, which specifically prevents mosquitoes from maturing into adulthood. The district stated the insecticide is eco-friendly, short-lived in the environment and not harmful to birds, fish, other insects, wildlife or humans.
A helicopter will disperse the treatment for a few hours, starting at approximately 7:30 a.m. No residential areas will be sprayed. The helicopter may make low-altitude passes over trails surrounding the treatment area, so the marsh trails will be closed to the public at that time and the public is advised to avoid the area.
"Recent warm weather provided the ideal environment for mosquito larvae to develop in hard to reach areas of the marsh," Vector Control District Manager Dr. Nayer Zahiri said. "These targeted treatments will help significantly reduce the adult mosquito populations in the area and lessen public disturbance."
A map of the area to be treated can be found at SCCVector.org.
Separately, the district confirmed that West Nile virus has been found in adult mosquitoes collected from portions of the 95054, 95051, and 95050 ZIP codes, which include parts of the city of Santa Clara. The map is posted here.
For free assistance with residential mosquito control, the public can contact the district office by calling 408-918-4770 or filling out a service request online at SCCVector.org.