This study aims to analyze the effect of B. bassiana on O. rhinoceros larvae. The samples used were 30 healthy 3rd instar O. rhinoceros larvae weighing 10-16 gr with a body length of 7-10 cm that were obtained from the field. The study consisted of two treatments with 10 replications, namely P1 (2 gr B. bassiana kaolin formulation/200 gr media) and P0 (Control). Observations were made every 2 days until all treated larvae was dead. The results showed that the larvae of O. rhinoceros infected with B. bassiana in the kaolin formulation died in a stiffness state and were covered with white powdery fungal hyphae on the surface of the larval body. Larvae died from B. bassiana on the 8th day after treatment and all larvae died (100%) on the 20th day after treatment. None of the O. rhinoceros larvae in the control treatment experienced death until day 20 after treatment.