SAN JOSE, Calif. (KRON) — After an exceptionally rainy winter, Santa Clara County has a surplus of stagnant water, creating ample breeding sources for mosquitoes.

The county’s Vector Control District began using drones this week to control mosquito larvae along San Francisco Bay and help prevent West Nile virus.

West Nile virus is a significant public health concern, county officials said. The California Department of Public Health considers it the state’s most common and severe vector-borne disease, causing more than 7,000 human infections and nearly 400 deaths since 2003 when it was first detected in California.

“It is critical for the District to access and treat marshland and other remote, non-residential areas in Santa Clara County that serve as breeding habitat for mosquitoes, which can transmit West Nile virus and other diseases once they mature. Some mosquitoes found in the Bay Area can fly up to 25 miles once they become adults,” county officials wrote.

Mosquitoes are typically most active in the summer and fall, as warm weather speeds up their life cycle.

This is the first year that Santa Clara County is deploying drones to mosquito-infested waters.

Edgar Nolasco, Director of the County’s Environmental Protection Agency, said, “Applying larvicide with drones is precise and effective and minimizes disruption to the ecosystem along the Bay.”

The drone program will focus solely on mosquito larvae to eliminate larval before they become adults.

The district strongly encourages residents to eliminate any sources of stagnant water on their properties. “Mosquito control is a community effort. To protect yourselves and your neighbors from mosquito-borne diseases, we encourage you to regularly check your property for sources of standing water and remove them,” Nolasco said.

Here are some things you can do to eliminate mosquito-breeding sources on your property:

  • Inspect for standing water on a weekly basis.
  • Drain or turn over anything that can hold water, such as flowerpots, planter bases, pet dishes, buckets and old tires.
  • Clean items like bird baths and pet bowls once a week to remove mosquito eggs.
  • Clear debris from rain gutters on a regular basis to allow water to flow.
  • Screen rain barrels, cisterns and irrigation drains to prevent mosquito access.
  • Fix leaky water faucets and broken sprinkler heads and avoid overwatering lawns and plants.
  • Ensure swimming pool water levels are adequate for proper circulation and filtration.

For free assistance with mosquito control or other vectors, residents can call the Vector Control District at 408-918-4770 or email Residents can also request free mosquitofish, which eat mosquito larvae, to place in neglected pools or spas, ornamental ponds, water troughs and other artificial bodies of water.

Most people infected with West Nile virus do not develop symptoms, while some may develop mild, flu-like symptoms, county officials said. People with compromised immune systems and the elderly are at higher risk of severe symptoms and even death, according to county officials.

When the district detects adult mosquitoes carrying WNV, it takes the additional step of conducting adult mosquito control treatments in the immediate area to reduce the risk of human infection.