Mosquito Spraying Planned Thursday

PALO ALTO, CA — The County of Santa Clara Vector Control District is set to conduct an aerial treatment for mosquito larvae in the Palo Alto flood basin on Thursday, March 20, weather permitting.

The nonresidential marshland, located along San Francisco Bay, is a breeding ground for winter salt marsh mosquitoes (Aedes squamiger), which can travel up to 20 miles and are known for their aggressive biting behavior.

The treatment will use a helicopter to apply a naturally occurring soil bacterium (Bacillus thuringiensis israelensis) and a mosquito hormone regulator (methoprene) to prevent larvae from maturing into adult mosquitoes. These pesticides, used by vector control districts across the Bay Area, are environmentally safe and do not harm birds, fish, beneficial insects, or humans.

“Our team has been monitoring mosquito larvae in the marsh, and recent rains have created pockets of water that we can’t reach on foot,” said Vector Control District Manager Dr. Nayer Zahiri. “If we don’t act soon, these larvae will become biting adult mosquitoes, affecting communities miles away.”

The aerial treatment will begin around 7:30 a.m. and last for several hours. The helicopter may make low passes over nearby trails, which will be closed to the public during the operation. The district advises visitors to avoid the area while treatment is underway, but all trails will reopen once it is complete.

Residents are encouraged to report daytime mosquito activity and take preventive measures, such as removing standing water from their properties and using insect repellent when outdoors. For more information or to request free mosquito control assistance, residents can contact the Vector Control District at (408) 918-4770 or visit the county’s mosquito prevention website.