The genus Trioxys Haliday, 1833 consists of more than 80 species worldwide with three species being recorded in South Korea. In this study, we report the first observation of the two additional species, T. liui Chou & Chou, 1993 from Takecallis arundinariae (Essig, 1917) on Phyllostachys bambusoides Siebold & Zucc., 1843 and T. remaudierei Starý & Rakhshani, 2017 from T. taiwana (Takahashi, 1926) on Sasa borealis (Hack.) Makino & Shibata, 1901.
Trioxys liui and T. remaudierei are described and reported with phototographs of the diagnostic morphological characters and the mitochondrial cytochrome c oxidase subunit I (COI) data (barcode region) and Bayesian tree of the phylogenetic analysis amongst the closely-related taxa are provided.