Neoplocaederus obesus (Gahan, 1890) is a wood borer with wide ranges of hosts, which was found on D. duperreanum Pierre in Zhongshan in the past few years, causing death of several trees. Data from field observations and larvae raised in lab were combined to investigate the life cycle of N. obesus in Zhongshan and its damages to D. duperreanum, which could provide basic information to the study of prevent and control of this species. This research also initially explores the production of calcareous cocoon of N. obesus larva before pupate by dissections and comparations. The results confirmed that the calcareous granules were produced and stored in the Malpighian tubules, and also suggested that mandibles should play an important role on secretion of calcareous granules or albuminous cement to making cocoons.