Tranfaglia, A. 1978 Considerazioni sull'affinita morfologica tra Planococcus citri (Risso) e Planococcus ficus. [Considerations on the morphological affinities between Planococcus citri (Risso) and Planococcus ficus (Signoret) (Homoptera: Coccoidea)].. Atti XI Congresso Nazionale Italiano di Entomologia. Portici-Sorrento, 1976, 91-93.

Notes: The author discusses microscopic morphological characters for the differentiation of Planococcus citri (Risso) and P. ficus (Sign.), which are species indistinguishable to the naked eye. The most valid distinguishing characters visible under the microscope are the multilocular pores of the metathorax, which are present only in P. ficus, and a complete absence of ventral ducts from the head (when it occurs), which is found only in P. ficus; auxiliary characters are the smaller number of pores on the prothorax and the larger number of ventral ducts in P. citri, but these are less certain. The species may be distinguished also by habits, since P. citri is polyphagous and P. ficus is known so far only on grapevine and fig.