Adult Batocera horsfieldi （Hope） were fed continuously with rose branches treated with diflubenzuron （DFB） at a concentration of 2．5、5．0、10．0、20．0、50．0、100．0mg／kg． The relationship between dynamic state of adults foodintake and that of progenyeggs hatchability was evaluated in the laboratory． When the concentration of DFB aqueous solution varied from 2．5mg／kg to 100．0mg／kg， the adults foodintake was inversely proportional to progenyeggs hatchability． On the basis of relationship mentioned above, we calculated the rate of the concordance between the dynamic state of adults foodintake and that of progenyeggs hatchability under conditions of different intervals． When the interval was 5、10、15、20d and 25d， the rate of concordance was 36．23％、57．97％、41．79％、65．57％、32．83％，respectively． It was concluded that the effective phase of chemosterilization by DFB in B． horsfieldi was about 10～20d． The results also showed that ingestion of DFB by progenyeggs was the main cause of sterile activities of DFB on the adult． The critical period when DFB in the hemolymph got into progenyeggs was the vitellogenesis stage． Insects whose oogenesis appeared in adult stage were apt to be sterilized by DFB． The optimal treating season was before the vitellogenesis stage．