The southern house mosquito, Culex quinquefasciatus, is a nuisance to residential communities from Palm Springs to the Salton Sea. Larvae breed in foul or highly polluted waters, typically in artificial containers, fish ponds, septic tanks, catch basins, waste treatment ponds, and neglected swimming pools. Birds are its principal blood meal source; however they will attack humans and invade homes. This mosquito has been found infected with encephalitis virus (eg., SLEV, WEE, and WNV) in California, but its role in the natural transmission of these viruses is considered to be secondary to that of Culex tarsalis in rural situations. In urban environments, Cx. quinquefasciatus is often the primary WNV vector.