The parasitizing behavior of the bathyluid Scleroderma guani on the pupa of the yellow mealworm, Tenebrio molitor Linnaeus was investigated in the laboratory. The parasitism process was divided into six stages，i. e. assembling, recognition, stinging, clearing and feeding, oviposition and protecting protelean bathylid. The recognition and stinging of the female bathylid to the pupa have much difference between female individuals. The time before stinging the host is 1.4－7.0 d , and the rate of the stinging is 8.7%-91.7%. The influence factors on the recognition and stinging rate included the female mating, host freshness and temperature. The stinging could keep the host alive and fresh, and made them suitable to be parasitized by the bathylid. On the average, the pupa of yellow mealworm was kept fresh for 12.6 days after being stinged. The average number of laying eggs for the S. guani is 30, and the biggest is 91. The eggs in the pupa body were evenly distributed, and this to facilitated the use of host nutrition by larvae of the bathylid. The female showed the behavior of protecting protelean bathylid, including protecting eggs and mustering old larvae. 6 Refs.