Culex nigripalpus: seasonal shift in the bird-mammal feeding ratio in a mosquito vector of human encephalitis.

Blood-engorged Culex nigripalpus (Theob.) collected throughout the year in two Florida localities were serologically tested to determine the host range of this mosquito in nature. A proportional increase in feeding on mammals occurred in early summer, reached a maximum between July and October, and was followed by a shift back to avian hosts which dominated the feeding pattern during winter and spring. This finding strengthens the hypothesis that a biphasic pattern of feeding is a basic characteristic of an enzootic vector that, in epidemic years, also serves as the primary vector of avian arbovirus to man.