SANTA CLARA COUNTY, CALIF. Beginning at approximately 8:00 a.m., Tuesday, April 29, 2014, the SCCVCD will apply a biological control agent and insect growth regulator by helicopter to reduce the emergence of adult mosquitoes. The areas to be treated are the Alviso Marsh, Smith Yard Marsh, New Chicago Marsh, and Owens Corning Marsh. Aerial treatment is necessary because the areas are extensive and difficult to be treated from the ground. No residences or businesses fall within the area to be treated. The aerial treatment is intended to minimize the number of mosquitoes and reduce the risk of mosquito bites to residents in the surrounding communities.
Commonly called the “summer salt marsh mosquito”, Aedes dorsalis lays its eggs in the moist soil just above the water line. These eggs can lay dormant for many years, even after repeated flooding. When they are re-flooded they hatch and begin a new cycle. Although this species has not yet been shown to transmit West Nile Virus, it is known to bite viciously during the day and can fly 5 miles from its breeding grounds to feed on humans and other mammals.
The District closely monitors the development of mosquito larvae in the areas to be treated. Current field conditions and mosquito growth trends indicate a high probability that a significant number of salt marsh mosquitoes will become adults in soon if left untreated. The mosquito fly-off may affect residents from the north coastal areas of the County
Aerial operations usually result in a 90 percent reduction in mosquito numbers, and dramatically reduce the extreme nuisance caused by these mosquitoes well into the summer.
Approximately 370 acres will be treated with water-based formulations of environmentally safe products: methoprene, an insect growth regulator, and Bacillus thuringiensis var. israelensis (Bti). Bti is a natural bacteria that, when consumed by mosquito larvae, produces an insecticidal protein that kills the larvae. These products are mosquito-specific and short-lived in the environment: they effectively control the immature (aquatic stage) mosquitoes, but are not harmful to birds, fish, other insects, wildlife, or humans.
Access to the areas will be restricted during aerial applications, but open to the public immediately afterward.