Karyotypes of 13 species from Taiwan (9 species) and from Holland (4 species) belonging to the families Aphalaridae, Psyllidae, Homotomodae, Carsidaridae, and Triozidae are described for the first time. Karyotypes ofBactericera maura, Cacopsylla hippophaeus, Dynopsylla pinnativena, Leptynoptera sulfurea, Macrohomotoma gladiata, Paurocepbala chonchainensis, P. sauteri, P. trematos, Sympauropsylla triozoneura, andTenaphalara acutipenniswere 2n= 24 + X0. However, the karyotypes of three species are as follows:Cacopsylla sorbi2n= 20 + XY,Heteropsylla cubana2n= 24 + XY, andTrioza remota2n= 14+ X0.