Comparative morphology of mouth parts of Zyginidia pullula, Empoasca vitis, and Graphocephala fennahi (Homoptera, Auchenorrhyncha)

Head and mouth structures of the mesophyllomyzous species Zyginidia pullula (Typhlocybinae), the phloemomyzous Empoasca vitis (Typhlocybinae), and the xylemomyzous Graphocephala fennahi (Cicadellinae) were examined and shown to be very similar. On the other hand, the ratios between the lengths of mandibular and maxillary stylets were closely comparable in the two typhlocybines, but lower than that of the cicadelline, and apparently correlated with the systematic group rather than with the trophic behaviour