Officials of the Santa Clara County Vector Control District (SCCVCD) utilized a Central Valley helicopter spraying service Thursday morning to control an increasing spread of mosquitoes in the Palo Alto Baylands.
The mosquitoes that were targeted are not known to carry West Nile Virus.
A breach in a tide wall that normally controls flow into the Baylands is allowing levels of water to crest more than a foot higher than normal, providing enhanced breeding territory for the "summer salt marsh mosquito," or Aedes dorsali. According to the Vector Control District, these mosquitoes have a vicious bite, and can fly up to five miles from their breeding grounds to feed on humans and other mammals.
Upwards of 300 acres of marshy, wet soil was sprayed with two products: methoprene, an insect growth regulator, and bacillus thuringiensis, a natural bacteria that, when consumed by mosquito larvae, activates an insecticidal protein that kills the larvae, according to the district.
The District says both products are environmentally safe.
"We have both the history and the science to prove the products we are using are completely safe to animals and humans," said Russ Parman, spokesman for the VCD.
Low volume aerosol applications - using a different chemical cocktail - were in Los Altos and Mountain View to fight off a different variety of mosquito carrying the potential for West Nile Virus.
In the fogging operation, sprays targeting adult mosquitoes were used at a rate of 1 fluid ounce per acre; in today's spraying targeting mosquito larvae, helicopters were set to spray at a rate of 10 gallons per acre.
Yesterday, in which the Vector Control District believes vigilant residents in our area have helped to create a very "mild year" for the spread of West Nile Virus.
The District continues to encourage residents to report mosquito-breeding sources and take preventive measures, such as wearing long-sleeved shirts and long pants, and applying repellent when outdoors where mosquitoes are biting.