Precipitating antisera with a high degree of specificity to mammalian and avian bloods were utilized in the study of 3,310 blood-engorged Culex tarsalis collected in Kern County, California. In the summer, 84.4 percent of feedings were on birds, including chickens, doves, and passerine species; and 13.9 percent of feedings were on mammals, including cattle, dog, horse, rabbit, and cat. In the winter, the proportion of feedings on birds increased, particularly on passerine species, with a concomitant decrease in feedings on mammals and doves. There was a very low proportion of nonreacting samples and few double feedings on different host species. Correlation of these data with epidemiologic and biologic data offers a clarification of the possible over-wintering reservoirs of arthropod-borne viruses and indicates the need for further studies on the influence of availability of various host species in a habitat as a controlling factor on the feeding habits of C. tarsalis.
School of Public Health, University of California, Berkeley, California.
Encephalitis Section, Technology Branch, Communicable Disease Center, U. S. Department of Health, Education, and Welfare, Bakersfield, California.