The biting activity of Culex ribeirensis was studied in the highland region of Southern Brazil and compared with data previously obtained in a lowland area of the same region. Hourly sampling with human bait showed a bimodal pattern, with a greater peak in the evening crepuscular period. Behavior was similar in both the highland area of Lupo Farm and the lowland of the Ribeira Valley but with a notable feature in the former. In relation to the vespertine crepuscular period, precrepuscular peaks were observed in the highland area. The adaptability of this species to man-made environments and its epidemiological significance are considered.
