Which two species of mosquito have been found in every county in California?

The species that have been found in every county in California are Culex pipiens and Aedes vexans. Culex pipiens, commonly known as the common house mosquito, is highly adaptable and has a wide distribution, which allows it to thrive in various environments throughout the state. Aedes vexans is another widely distributed species that is also resilient and can be found in diverse habitats.

This combination of species is representative of the general mosquito populations found in California, and their presence across all counties highlights their importance as vectors and their ability to survive and reproduce in varied conditions. Understanding these specific species is crucial for public health and vector control strategies, as they can potentially transmit diseases to humans and animals.