A series of experiments with different body parts of females Monochamus alternatus Hope separately dissected showed that after head, elytra and prothorax of females were separately dissected , or replacing the abdomen of females with that of males , females still elicited the mating behavior of males.This implied that if contact sex pheromone exists, it should be accumulated on the second half part of body of female M.alternatus , especially thorax .However , dead females killed by freezing did not elicited the response of males, and when both live and dead females killed by freezing were offered to males, all males preferred live females, further evidence suggests that contact sex pheromone does not exist in M.alternatus , and visual cues may play an important role in the mating behavior of M.alternatus since the movement of female beetle attracts male .When antennae of males were dissected at No .5-6 segment and No .1 segment of antennae , males still succeeded in finding females to finish the mating behaviors .This suggests that either contact sex pheromone does not exist ormales perceive pheromone on the receptors of maxillary and labial palps.Dead females from extraction with hexame did not also elicit the response of males. When the whole body was extracted with hexane or ether , both extracts dripped on dead females due to extract, glass sticks and cobblestones did not elicit the response of males.Further evidence showed that the contact sex pheromone maybe does not exist in the body of M.alternatus.Mature females and males aggregate on host stem by perceiving the host volatiles .In the small environment of host stem , visual cues may play an important role in the following mating behavior of M. alternatus.