Head and mouth structures of the mesophyllomyzous speciesZyginidia pullula(Typhlocybinae), the phloemomyzousEmpoasca vitis(Typhlocybinae), and the xylemomyzousGraphocephala 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