Over a three-year period, 10,229 blood-engorged Culex tarsalis were collected in rural areas of Kern County, California. These blood meals were identified with precipitating antisera prepared in birds and rabbits. C. tarsalis had a variable feeding pattern, showing a preference for passerine birds at all seasons but most pronounced in the winter. There was a significant increase in feedings on doves and mammals at the height of the summer. The feeding patterns reflected the abundance of different animal species in proximity to the collecting sites. Collections of C. tarsalis from habitats believed to favor feeding on man or rodents failed to yield any feedings on these hosts. Only six feedings on rodents and three on reptiles were detected. The feeding habits of C. tarsalis in Kern County would indicate that passerine birds and doves are the most likely hosts of Western equine and St. Louis encephalitis viruses.
School of Public Health, University of California, Berkeley, California.
Disease Ecology Section, Technology Branch, Communicable Disease Center, Public Health Service, U. S. Department of Health, Education, and Welfare, P.O. Box 1564, Bakersfield, California.