Drosophila suzukii and Drosophila melanogaster feed on various fruits, causing great economic losses. In order to find the optimum time for controlling D. suzukii and D. melanogaster, the daily rhythms of oviposition, egg hatch, pupation, adult eclosion, copulation, and feeding of these two pests were studied. We found the circadian rhythm of D. suzukii oviposition to have a single pattern with a peak from 20:00–24:00, while the peak oviposition of D. melanogaster was from 16:00–4:00 (the next day). Neither D. suzukii nor D. melanogaster showed a daily pattern of egg hatch; the single peak of egg hatch for D. suzukii occurred 24–32 h after oviposition, while that for D. melanogaster followed a bimodal pattern, with the first peak of egg hatch from 0–4 h after oviposition and the second from 32–36 h after oviposition. Pupation in D. suzukii showed a single peak from 8:00∼16:00, while in D. melanogaster pupation followed a bimodal pattern, with peaks from 4:00–8:00 and 12:00–20:00. Eclosion of of D. suzukii adults followed a unimodal pattern, and generally took place from 0:00–8:00, while that of D. melanogaster also showed a single peak, generally from 0:00–12:00. Meanwhile copulation of D. suzukii, which showed a bimodal pattern, was concentrated from 0:00–12:00 and 20:00–24:00 (the next day), while copulation of D. melanogaster showed a single peak, generally from 0:00–12:00. Both D. suzukii and D. melanogaster had a preference for feeding in light, and in a 24 h photoperiod the percentages of feeding insects were 80.8and 81.1, respectively.