The foraging activities, including foraging range and seasonal fluctuation of the Formosan subterranean termite, Coptotermes formosanus Shiraki, were investigated in subtropical areas in China. Six mature C. formosanus colonies were selected for this study. Foraging distance and area were conducted in Anqing1, Hengyang, and Wuxi1 colonies, while the seasonal fluctuation was conducted in Wuxi2, Wuwei, and Anqing2 colonies. Mark—release—recapture method analysis showed that the Formosan termites foraged at least 11.5, 28.7, and 56.8 m away from the main nest and covered 98.1, 543.7, and 671.9 m² of foraging area at Anqing1, Hengyang, and Wuxi1 site, respectively. The seasonal fluctuation in termite colony activity showed an “M shape” pattern according to the wood damages caused by termites at monitoring stations. Peak colony activity at Wuxi2, Wuwei, and Anqing2 occurred in July and October, June and September, July and October, respectively. This study provides critical information for the integrated management of C. formosanus, including baiting application in the subtropical regions of China, where it constitutes the most destructive pest for household structures.