Abstract
Mosquito collections by using light traps have been carried out at 10 to 11 stations in Kyoto City area at intervals of about 10 days every year. Mean percent indexes (MPI), being calculated from the data of mosquito collections, were used for comparison of the annual abundance of mosquitoes. It is no doubt thatCulex tritaeniorhynchus summorosushas decreased recently and this decrease is correlated with the reduction of human patients of Japanese encephalitis. Wide use of two herbicides, CNP and nitrofen, for rice plant cultivation, may probably be one of the reasons for the decrease of the mosquitoes.
