Abstract: The genetic analysis was conducted by crossing experiments to use 5 strains of B.xylophilus from China,Japan,Canada and 5 strains of B.mucronatus from China,Japan,France.The results indicated that the two species of China might cross successfully,but the number of hybrids were limited and hardly fertile,so the two species were different in genetics.There was no difference in the strains of conspecies from China.When the two Chinese species were crossed with the strains of Japan,France,and Canada respectively,there was ovious difference in interspecific crossing and some difference in intraspecific crossing.The F1 generation females of interspecific hybridization had mucronate tails similar to B.mucronatus in reciprocal crossing.Back crossing of F1 hybrid females to their parent males were more difficult to produce progeny.The rate of deformations in hybrid adults ranged 10%～60%.Major deformations were no spicules in males and crooking of bodies in females and larvae.