HAYWARD, Calif. August 11, 2025 — The Alameda County Mosquito Abatement District has confirmed the discovery of two adult Aedes aegypti mosquitoes in Livermore on August 8th. This marks the first detection of the invasive species in the city. The District is working with city officials and volunteer groups to inform residents and inspect properties.

Aedes aegypti is not native to California and can transmit diseases such as dengue, Zika, and yellow fever. In response, District staff are going door-to-door in the two detection zones to inspect and treat potential mosquito breeding sites, along with conducting intensive follow-up trapping.

“Our active mosquito monitoring program detected Aedes aegypti for the first time in the City of Livermore,” said General Manager Ryan Clausnitzer. “We responded by inspecting public and private properties near the detection zones in cooperation with Livermore residents, business owners, and City staff. The quickest way to prevent this annoying and potentially dangerous mosquito species from becoming established is to act now. We urge residents to grant yard access so we can ensure no one is accidentally breeding mosquitoes.”

The two detections occurred in separate locations. The first was found in an industrial area near the Livermore Water Reclamation Plant, between Isabel Avenue and Jack London Street. The second was identified southeast of Jack Williams Park, between Holmes Street and Alden Lane. Residents may see District staff in uniforms with official logos and identification. Staff will be inspecting yards and outdoor spaces for mosquito breeding sites.

For questions or concerns, visit www.mosquitoes.org or call (510) 783-7744.

Aedes aegypti is an aggressive, daytime-biting mosquito that often targets ankles. It is a container breeder, laying eggs just above the waterline in small, artificial sources such as buckets, pet dishes, fountains, birdbaths, plant saucers, and old tires. Eggs can survive for over a year without water. Scrubbing containers helps dislodge eggs and prevents them from being moved to new locations. The District’s goal is to prevent this species from becoming permanently established in Alameda County.

The District urges residents in Livermore—and throughout Alameda County—to inspect their properties for standing water, which can serve as mosquito breeding habitat. Aedes aegypti eggs are tiny and can be mistaken for dirt or seeds. This mosquito can develop from egg to adult in as little as the water held in a bottle cap. Adult mosquitoes are less than a quarter-inch long, with black and white stripes on their backs and legs. They typically bite people and do not travel far—generally less than 300 feet from where they hatch.

If Aedes aegypti becomes established in Alameda County, it could threaten public health and quality of life, as these mosquitoes are highly aggressive and active during daylight hours. While not native to California, Aedes aegypti is now found in at least 26 counties statewide, including nearby counties.

Protect Yourself from Mosquito Bites:

·     Apply insect repellents containing EPA-registered ingredients such as DEET, picaridin, IR3535, or oil of lemon eucalyptus.

·     Wear long-sleeved shirts, pants, socks, and shoes when mosquitoes are most active.

·     Ensure window and door screens are in good condition.

·     Report daytime mosquito activity immediately to the Alameda County Mosquito Abatement District at (510) 783-7744 or www.mosquitoes.org.

If you develop a fever, headache, and joint or muscle pain after returning from an area where dengue, chikungunya, yellow fever, or Zika is present, contact your doctor. Use mosquito repellent for three weeks and stay indoors as much as possible to avoid mosquito bites and prevent the possible spread of disease.

For more information, visit www.mosquitoes.org.

Alameda County Mosquito Abatement District

Media Contact

Judith Pierce

Public Education Officer

510-783-7744