Components of vectorial capacity (biting density, survival, and host preferences) of a population of Aedes (Finlaya) poicilius, the principal vector of Wuchereria bancrofti in the Philippines, were studied in 1994-1995 in Sorsogon province. Aedes poicilius comprised 20.7% of 3243 mosquitoes of 24 species taken in 42 nights of human-biting collections, and 1.4% of 7586 mosquitoes of 27 species taken in 18 concurrent nights of carabao-trap collections. There were, on average, 16 bites by Ae. poicilius per person per night. As there was no relationship between body size of the female Ae. poicilius and parity status, body size was not a variable affecting survivorship of Ae. poicilius. The probability of daily survival was estimated to be 0.85, and the human blood index was 0.67. None of the 862 Ae. poicilius examined contained W. bancrofti larvae, probably because of distribution of diethylcarbamazine to microfilaraemic people prior to the study. The vectorial capacity of the Ae. poicilius population under study was estimated to be 2.4 new cases per primary case per day. However, the basic reproductive rate (i.e. the number of new cases of W. bancrofti infection generated from a single infective case) was estimated to be very low because of inefficiency in parasite transmission.