- The larvae are found in clear or foul water in a variety of habitats including ditches, irrigation systems, ground pools, marshes, pools in stream beds, rain barrels, hoofprints, and ornamental pools. Foul water in corrals and around slaughter yards appear to be favorite larval habitats in many localities. Cx. tarsalis are biters, attacking at dusk and after dark, and readily entering dwellings for blood meals. Domestic and wild birds seem to be the preferred hosts. and man, cows, and horses are generally incidental hosts. (Carpenter and LaCasse 1955:296)
- Culex tarsalis is believed to be the chief vector of western equine encephalitis virus under natural conditions. The virus has been isolated from wild-caught C. tarsalis on several occasions in areas in which the disease was both epidemic and epizoitic. The viruses of both St. Louis and California encephalitis have been isolated from this mosquito. (Carpenter and LaCasse 1955:296) It is also a vector of West Nile Virus.