The wax gland plates of 58 species in 26 genera of three tribes of Hormaphidinae, a group of aphids with wax gland plates typical of aphids as a whole, are studied. We systematically analyzed the morphological diversity of wax gland plates in this group and discussed possible scenarios for their evolution. The results suggest that wax gland plates in Hormaphidinae show great diversity in four aspects: distribution, degree of development, shape and structure. In addition, ontogenetic changes in wax gland plates are found in several species. Wax gland plates with six rows on the dorsum appear to be the primordial type and there is a general trend for the degeneration of wax gland plates in Hormaphidinae. Wax gland plates appear to contain certain phylogenetic signals and consequently may be of great importance to phylogenetic and evolutionary research on aphids.