Contra Costa County is home to 23 native species of mosquitoes.

Earlier this month the Contra Costa Mosquito & Vector Control District (District) found a non-native species of mosquito, Aedes aegypti, in a residential area of Martinez, south of Highway 4. This is an invasive species that can transmit the causative agents of Zika, Dengue fever, Chikungunya, and Yellow fever.