Nematus yokohamensis (Konow, 1895) is redescribed. Pristiphora geniculata (Hartig, 1840) is recorded from Japan (Hokkaido and Honshu) for the first time. New distribution records within Japan are Nematus yokohamensis from Kyushu and Pristiphora conjugata (Dahlbom, 1835) from Hokkaido. New host plant records are given for Abia fasciata (Linné, 1758), Athalia yanoi Takeuchi, 1952, Macrophya fascipennis Takeuchi, 1933, M. katayamai Shinohara, 2020, M. timida Smith, 1874, Mesoneura shishikuensis Togashi, 1965, Nematus japonicus (Takeuchi, 1921), N. yokohamensis, Perineura okutanii Takeuchi, 1959, P. pictipennis Takeuchi, 1959, Pristiphora geniculata, Profenusa thomsoni (Konow, 1886) and Taxonus japonicus Takeuchi, 1929. Additional information on the larval food plant is given for Nesoselandria morio (Fabricius, 1781). The larvae of Fagineura glabella Hara, 2022, Macrophya fascipennis, M. katayamai, M. timida, Mesoneura shishikuensis, Nematus yokohamensis, Perineura okutanii, P. pictipennis and Taxonus japonicus are figured and briefly described for the first time.