Northern House Mosquito (Culex pipiens)

Present year-round. Breeds in foul or polluted water. Feeds on birds and mammals, including humans. Readily enters buildings and bites indoors. Can transmit West Nile virus, Western Equine Encephalitis, and St. Louis Encephalitis.

Western Encephalitis Mosquito (Culex tarsalis)

Present primarily spring through fall. Breeds in a wide range of habitats. Prefers birds, but often feeds on humans at night. This mosquito is the primary vector of West Nile virus, Western Equine Encephalitis, and St. Louis Encephalitis. 

Tule Mosquito (Culex erythrothorax)

Present June through October. Breeds among tules or cattails. Opportunistic feeder; will feed on birds and humans. Can transmit Western Equine Encephalitis and St. Louis Encephalitis.

Cool Weather Mosquito (Culiseta incidens)

Present year-round. Breeds in clean, cool water with some shading. Actively feed on humans at dawn and dusk. Can be a local pest.