To estimate effective degree days of dominant caddisfly species in Uji River, river temperature was recorded and caddisfly adults accumulated on lights near riverbank were collected at nighttime for every 4-5 days from early spring to late autumn in 2014. Based on the temporal changes in catch number and wing size of individuals, 4 generations of Hydropsyche setensis and 3 generations of Macrostemum radiatum were recognized. Effective degree days of these species, which were estimated from cumulative temperature above lower temperature threshold between two successive generations, were comparable to a reported value of related species or to a reported voltinism in a given temperature pattern. Existence of upper temperature threshold (thermoinhibition) for development, which has been less reported for caddisflies, was also suggested for these species. Our results would make some predictions for the timing or duration of caddisfly emergence in Uji River possible from river temperature data.