Abstract
During the period from January to December in 1965 and 1966, investigations on the annual succession of mosquito larvae occuring in tree holes were made in a zelkova forest in the suburbs of Ashikaga City, Tochigi Prefecture. 1) The mosquito larvae and pupae obtained were 1, 029 individuals in 1965 and 945 individuals in 1966, and they were classified into 3 genera and 3 species in every year; Uranotaenia bimaculata 81.6% (1965) and 89.7% (1966), Aedes albopictus 9.3% and 5.4%, and Tripteroides bambusa 9.0% and 4.9%. 2) The seasonal prevalence of the mosquito larvae and pupae collected in both years was summarized as follows. Ae. albopictus and Tr. bambusa appeared first in mid-April; the former was collected until mid-October, while the latter until late September. Ur. bimaculata occured first in early July, and increased suddenly in number in early August when the above two species declined in number. Thereafter, this mosquito reached the maximum abundance during the period from late September to mid-November, and disappeared after the middle of December. 3) None of the mosquito larvae overwintered in the tree holes investigated, because the water of them dried up or froze in a frigid winter.
