Abstract: The tail terminals of 3 strains of B. xylophilus from China,Canada,Japan and 3 strains of B. mucronatus from China, France,Japan were measured,and the shapes of male spicule from the 6 strains were observed at the same time. The results indicated that the size of tail terminals was stable. As for the shape of male spicule, there is no obvious difference between the interspecific strains. So it is not suitable to take the male spicule as a taxonomic characteristics.