The aphid Nipponaphis distyliicola (Hormaphidinae, Nipponaphidini) host alternates between Distylium racemosum and evergreen oaks such as Quercus glauca or Q. myrsinifolia in Japan. The sexuparae produced on the oaks fly to D. racemosum and, on its leaves, give birth to first-instar sexuals which develop into dwarfish adults. It has been unknown how many times they molt to reach the adult stage. Through rearing them individually in slender glass vials we confirmed that the female molts four times as usual aphids do but that the male molts only twice. The adult male and female of N. distyliicola are described, and morphological differences found in the first instar between sexes are also mentioned.