Abstract: The paper aims to reveal the reasons for the disease infection of the whole konjac plant caused by the petiole bases bitten by pillworm, so as to clarify the inter-relationship between insect pests and disease of konjac, and provide a theoretical basis for pest control in field. The authors adopted field investigation and indoor artificial feeding. Field investigation showed that the petiole bases of konjac were bitten by pillworm, then resulted in infection of the plant in Ankang, Hanzhong, Baoji and so forth, and most infection happened in wet and shady places; laboratory experiment showed that pillworm mainly bit konjac leaves and petiole bases. Besides, the biting degree of pillworm on konjac was different according to varieties. The above results prove that pillworm is a new kind of pest of konjac and an inducer of konjac disease.