Mosquito collections were made in Chichi-jima, Ogasawara Archipelago in May 1990 and 7 species were identified. Culex mimeticus is a new record for Chichi-jima. The larva of Cx. boninensis was found commonly in ground pools and artificial containers around the dwellings and it was easily colonized in the laboratory. Culex boninensis was stenogamous; copulation took place easily on the wall of a small plastic container (3cm diameter×5cm deep) and it fed easily on chicken, Mongolian gerbil and mouse in this order. Mating took place 8 hours after emergence of both sexes in the container. The insemination rate of the females in the container was about 90%, 2 days after emergence. A mature male copulated with 7-16 mature females in the container during a 24-hr period. The same experiments were carried out for Cx. quinquefasciatus collected in Chichi-jima for comparison.