Massive flights of chironomid midges have been observed frequently, and they have causedsome problems in the daily life of residents around water treatment works. The development of physical andbiological control strategies against chironomid midges is urgently needed because chemical control rs notfeasible in slow sand filter beds. In this study, in order to collect basic biological data for controlling the massiveflights of chironomid midges, seasonal changes in the abundance and species composition of chironomid midgesand larvae were investigated in slow sand filter beds. We identified 21 genera and...