Ecology of vector mosquitoes of Japanese encephalitis, especially of Culex tritaeniorhynchus summorosus, 5. Overwintering of Culex tritaeniorhynchus summorosus and Anopheles sinensis.

The time of awakening from winter diapause in Culex tritaeniorhynchus summorosus and Anopheles sinensis was examined from the data of mosquito catches in winter and early spring from 1965 to 1971 in the Nagasaki area. The results indicated that at least until the end of February most females of G. t. summorosus are still in a diapausing state, i. e., they do not feed on animals even on a warm day, while many of An. sinensis females are in such a physiological state already in January that they can feed on animals if the temperature is high enough for their flight activity. From the observations in the field and the experiments in the laboratory, it was implied that the main overwintering place of C. t. summorosus, and probably An. sinensis too, is the underground small space of stone walls, banks and the likes which are common in the terraced rice field area.