The Aedes aegypti mosquito, also known as the Yellow Fever Mosquito, has been confirmed in both Sutter and Yuba Counties, signaling a continued northward progression of the invasive species in California.
The Sutter-Yuba Mosquito & Vector Control District is implementing its Invasive Aedes Response Plan to combat the infestation and mitigate the public health risk posed by this aggressive, daytime-biting insect.
Spread Reaches San Francisco Bay Area
The aggressive spread of the Aedes aegypti population is continuing throughout Northern California, now reaching the San Francisco Bay Area.
The County of Santa Clara Vector Control District recently announced the detection of Aedes aegypti near Kelley Park in San Jose. This marks the first time the species has been found in this particular area of San Jose, indicating the mosquito has likely become established in Santa Clara County. Health officials note the population has been spreading steadily throughout Northern California since the spring.
Confirmed Detections and Spread
The first detection in the Sutter-Yuba area was made in August 2020 in Yuba City, Sutter County. More recently, in July 2023, the mosquito was confirmed in Olivehurst, Yuba County.
The Aedes aegypti mosquito, a tropical and subtropical species identified by a distinctive lyre-shaped marking on its back, was first found in California in 2013 and has since spread to 27 counties, particularly in Southern California and the Central Valley.
This mosquito, along with two other invasive species—the Asian Tiger Mosquito (Aedes albopictus) and the Australian Backyard Mosquito (Aedes notoscriptus)—are small, black-and-white striped insects often arriving as dormant eggs in imported goods like tires or hitchhiking on various forms of transportation.
Disease Transmission Risk Escalates
While Yellow Fever, Dengue, Chikungunya, and Zika viruses are not currently transmitted locally in the Sutter-Yuba area, the presence of the Aedes aegypti mosquito creates a significant public health vulnerability. This species is a capable vector, meaning it can transmit these diseases to people.
The concern lies with infected travelers: a mosquito could pick up a virus by biting an infected person who has returned from an endemic area and then spread it to other people, establishing a cycle of local transmission. Humans thus serve as reservoirs for the viruses, and the invasive mosquitoes act as the carriers.
Recent reports underscore the mounting risk:
- Los Angeles County recently reported its first case of locally acquired dengue for the 2025 mosquito season, with Aedes aegypti the likely culprit.
- The State of New York also confirmed its first locally acquired case of chikungunya virus in six years.
The Aedes aegypti has the ability to “move with people,” whether by following them into a car or home, or by breeding in extremely small containers, which accelerates its spread.
Control Efforts Underway
The Sutter-Yuba Mosquito & Vector Control District is actively working to define the scope of the infestations. Staff are conducting surveillance using specialized mosquito traps and, once the infestation’s extent is clear, will begin control measures. These efforts involve using a multitude of integrated pest management tools to target the egg, larval, pupal, and adult stages of the mosquito.
Critical Role for Residents: How to Stop the Spread
Residents are crucial partners in stopping the spread of these invasive mosquitoes, which are known to be aggressive, sneaky, and bite during the day. These mosquitoes lay their eggs in containers of standing water both indoors and outdoors. Even when dry, the eggs can survive for months, only to hatch when they contact water again. They commonly breed in saucers under potted plants (which should be filled with sand), pet water dishes, and clogged rain gutters.
The District urges residents to follow four critical steps:
- Report Sightings: Call the local mosquito and vector control district if you see or are bitten by a small, black-and-white mosquito during the day.
- Drain and Dump: Eliminate all standing and stagnant water around your home and property. Get rid of any unnecessary items that could hold water. Keep pet dishes, bird baths, and kiddy pools scrubbed, clean, and fresh.
- Use Repellent: Apply insect repellents containing EPA-registered active ingredients like DEET, Picaridin, or oil of lemon eucalyptus to avoid bites from all mosquitoes.
- Do Not Transport: Avoid moving or sharing potted plants with saucers or plant stems rooted in water, as these containers can be contaminated with mosquito eggs.
READ: Hillsborough County Helps Battle Dengue With Mosquitofish Giveaway
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