The aphid genus Stomaphis Walker, 1870 (Hemiptera: Aphididae: Lachninae) is Palaearctic origin group with 30 valid species. It is associated with variable woody host plants, having very long rostrum, which enables them to feed crevices in thick bark of trees. In this study, Stomaphis (stomaphis) pini pini is newly recorded in the Korean Peninsula on Pinus densiflora (Pinaceae). We described morphological features of alate viviparous females, apterous males and oviparous females, respectively. Furthermore, little known forms, sexual morphs of giant oviparous females and dwarfish apterous males are observed.