Six nominal species of gall midges (Diptera: Cecidomyiidae) originally assigned to four separate genera and recognized here as three valid species are transferred to Arnoldiola Strand. They are as follows: Arnoldiola azaleae (Felt 1907a), new combination (from Oligotrophus Latreille); Arnoldiola caudata (Felt 1915), new combination (from Phytophaga Rondani) and new synonym of A. azaleae; Arnoldiola brevicornis (Felt 1907a), new combination (from Janetiella Kieffer); Arnoldiola tiliacei (Felt 1907a), new combination (from Janetiella) and new synonym of A. brevicornis; Arnoldiola castaneae (Felt 1909), new combination (from Rhopalomyia Rübsaamen); and Arnoldiola ligni (Felt 1915), new combination (from Janetiella) and new synonym of A. castaneae. Diagnostic characters of the genus are outlined, and the newly combined species are described with some characters illustrated.