Abstract: To explore the pathogenesis of infection with Heterorhabditis bacteriophora in white grubs, the activity of phenoloxidase (PO) and carboxylesterase (CarE) in hemolymph, as well as protein and trehalose content, between infected grubs and control were observed. The change tendencies of the PO and CarE activities in infected grubs were similar. At 24, 12, 36 h after infection, the PO activities in the 2nd instar larvae of Holotrichia oblita Faldermann, H parallela Motschulsky and Anomala corpulenta Motschulsky reached maximum and were significantly higher than each control (P<0.05), respectively. Similarly, after 48, 36, 48 h of infection, CarE activities in the three white grubs ran to maximum respectively, significantly higher than control (P<0.05). The protein content in hemolymph of 3rd instar A. corpulenta larvae increased greatly after 20 h of infection then decreased dramatically at 28 h. The trehalose content reached the highest at 20 h, and lowest at 28 h. These changes were significant difference against the control (P<0.05). Taken together, it indicated that H. bacteriophora could affect the immune system and metabolic processes in white grubs. These results laid a foundation for further analysis of pathogenesis of infection with H. bacteriophora in white grubs.