The District Will Be Releasing Male Aedes aegypti to Reduce the Population of these Dangerous Mosquitoes
The Contra Costa Mosquito and Vector Control District (District) continues to work to control the invasive Aedes aegypti mosquitoes that can transmit the viruses that cause Zika, dengue fever, yellow fever, and chikungunya. The District has detected this dangerous mosquito in Antioch for three consecutive years.
In an effort to control these mosquitoes in Antioch, the District will begin a pilot project to use a form of Innovative Mosquito Reduction (IMR) beginning July 7, 2026.
This form of IMR involves the release of male Aedes aegypti mosquitoes that have been treated with Wolbachia bacteria. These naturally occurring bacteria do not impact humans or pets, and male mosquitoes cannot bite. Once released, the Wolbachia-treated male Aedes aegypti mosquitoes mate with the female Aedes aegypti mosquitoes in the area, exposing the female mosquitoes to the Wolbachia strain. This exposure causes them to lay eggs that do not hatch, reducing the population of these mosquitoes over time.
What Do Antioch Residents Need to Do?
There is nothing Antioch residents need to do related to the IMR activity, as the District will be working in a small area of Antioch, and male mosquitoes do not bite.
It does remain critically important for all Contra Costa County residents to walk around their properties at least once a week and dump out any amount of standing water to prevent mosquito production on their properties.
Why is the District Using IMR and Releasing Male Mosquitoes?
For the past three years, the District has been working to control Aedes aegypti mosquitoes, an invasive species not native to California, in Antioch. In response, the District has been going door-to-door to check every front and back yard in the areas of concern, but it is difficult to get into every property. The District has also used more traditional versions of larval mosquito control, including wide-area larval control (WAL) and adult mosquito control products to prevent these mosquitoes from spreading, with limited success.
The District will release the Wolbachia-treated male mosquitoes in a small area of Antioch weekly from July through October with the goal of reducing the number of wild mosquitoes over time within the target area.
If this project yields satisfactory results, the District may expand the use of IMR in the future. Meanwhile, if residents notice the District’s mosquito traps or an increased number of male mosquitoes in their neighborhood, know that they are there to protect you and your family against dangerous invasive mosquitoes and the diseases they carry.
