Bemisia tabaci (Hemiptera: Aleyrodidae) is one of the most important insect pests in the world. In the present study, the taxonomic status of B. tabaci and the number of species consisting of the B. tabaci complex were determined based on 1059 COI sequences of B. tabaci and 509 COI sequences of 153 hemipteran species. The genetic divergence within B. tabaci was conspicuously higher (onaverage,11.1%) than interspecific genetic divergence within the respective genera of the 153 hemipteran species (on average, 6.5%). This result indicates that B. tabaci is composed of multiple biological species that may belong to different genera or subfamilies. The phylogenetic tree constructed based on 212 COI sequences without duplications revealed that the B. tabaci complex is composed of a total of 31 putative species, including a new species, JpL. However, genetic divergences within five species, Asia III, Asia II 7, Mediterranean, New world, and Sub Saharan Africa 1, were higher than 3.5%, which has previously been used as a threshold of genetic boundary in distinguishing species of the B. tabaci complex. These results suggest the necessity to redefine the threshold for species boundaries to best distinguish the constituent species in the B.tabaci complex.