Abstract: Cacopsylla citrisuga Yang & Li is a major pest of Citrus limon (L.) Burm.F. in Dehong lemon production region, Yunnan Province. The pest damages the young leaves and flushes of lemon trees. A recent study indicated that C. citrisuga was a carrier of Candidatus Liberibacter asiaticus, the bacterium associated with Asian type huanglongbing. This work was therefore initiated for study of the morphological characters, biology, population dynamics and economic damages of the psyllids in Dehong region. The study indicated that C. citrisuga preferred areas with an altitude between 1 000-1 500 meters. Its host plants were limited to the species of in genus Citrus as well as Poncirus trifoliate only. The pest caused more severe and a longer period of damage as altitude increased. The nymphs caused the most damage. The common symptoms of C. citrisuga infestation include distorted leaves. Population dynamics and occurrence of C. citrisuga are correlated with lemon flushing, altitude, and temperature.