Supplementary morphological descriptions of five Cecidophyopsis species collected in Europe (Serbia, Austria, Italy and Montenegro) are given: Cecidophyopsis vermiformis from Corylus avellana L. (Betulaceae), C. hendersoni from Yucca gigantea Lem. (Asparagaceae), C. verilicis from Ilex aquifolium L. (Aquifoliaceae), C. psilaspis from Taxus baccata L. (Taxaceae) and C. malpighianus from Laurus nobilis L. (Lauraceae). Males of C. vermiformis, C. verilicis, C. hendersoni and C. malpighianus, and immatures of C. hendersoni and C. verilicis, are described for the first time. C. verilicis is recorded for the first time in the fauna of Serbia and the European region. Female cuticle-lined internal genitalia of five Cecidophyopsis species are studied under confocal laser scanning microscopy. A several steps of oviposition in cecidophyines is proposed based on CLSM observations on their internal genitalia. Sequences of the barcoding region of the mitochondrial cytochrome oxidase subunit I (mtCOI) gene are given for the following species: C. hendersoni, C. verilicis, C. psilaspis and C. malpighianus.