More Invasive Mosquitoes Found in Contra Costa County

CONCORD, CALIFORNIA – The Contra Costa Mosquito and Vector Control District (District) has once again identified the invasive mosquito species capable of transmitting the pathogens that can cause Zika virus, Dengue fever, and Yellow fever, Aedes aegypti in Contra Costa County — this time within the city of Antioch below Highway 4 and between Mountaire Drive and the Contra Costa Canal.

This is the second location in 2024 where invasive mosquitoes have been reported in Contra Costa County. Last month, several Aedes aegypti mosquitoes were found in the District’s West Nile virus surveillance traps in North Concord. In 2022, the invasive species were discovered for the first time in Contra Costa County in the city of Martinez.

The District is currently conducting door-to-door inspections, additional surveillance, and trapping in the area of Antioch where these mosquitoes were identified, with the goal of eliminating them before they become established in Contra Costa County; however, they are known to be very difficult to eradicate.

“During a recent residential inspection, one of our technicians was provided with three mosquitoes, which were subsequently identified as the invasive species Aedes aegypti,” said Steve Schutz, Ph.D., Scientific Programs Manager. “We appreciate residents doing their part to protect public health by reporting neighborhood mosquito issues.”

Aedes aegypti mosquitoes are very small (about 1/4 inch), with black bodies and white stripes. They were first introduced to Southern California more than 10 years ago. Since then, they have moved from Southern California to Shasta County and are now established in 24 counties across the state. Because these mosquitoes lay sticky eggs above the water line in any size container that holds water, they can be transported to new areas easily and are often introduced through travel, particularly as people move from area to area and may unknowingly transport these mosquitoes in potted plants or other outdoor containers.

To reduce the risk of these mosquitoes, it is important that residents:

• Dump out any amount of standing water.
• Scrub the now-empty bird baths, containers, outdoor pet dishes, garden pots for plants, and anything else that can hold water outdoors to remove the stick eggs.
• Report any day-biting mosquitoes by calling the District at (925) 685-9301 or online.

For residents in the area where the District conducted door-to-door inspections, if you were not home at the time and you received a door tag asking you to contact the District to reschedule an inspection, please do so promptly as the District strives to find the source of these mosquitoes and stop them before they become established.

Contra Costa Mosquito and Vector Control District, an independent special district and public health agency, is located at 155 Mason Circle in Concord.

Previous Stories:

• Aug 30 – More West Nile Virus-Infected Mosquitos and Another Invasive Mosquito Confirmed in Contra Costa County
• Aug 27 – Invasive Aedes Aegypti Mosquito Found Again in Contra Costa County
• Aug 9 – West Nile Virus-Infected Mosquitoes Confirmed in Oakley
• July 26 – First West Nile Death Since 2006 Reported in Contra Costa County