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.

The subfamily Lachninae Herrich-Schaeffer, 1854 consist of about 400 species belonging to 19 genera world-wide. Lachninae are distributed mostly in the Nearctic, Oriental and Palaearctic Regions. Their host plants are known as grasses, deciduous tree and conifers. Taxonomic study of Lachninae has been dealt with some authors in several countries, whereas it has rarely performed in the Korean Peninsula after Lee et al. (1994). Here, we review the subfamily Lachninae from the Korean Peninsula, focusing on its taxonomic history and diversity.

The genus of Stomaphis (Aphididae: Lachninae) is stem or root feeding aphid on trees and can easily be distinguished in having the very long rostrum which extends beyond the length of body. Most of species are monoecious holocyclic without host alternation and attended by ants. Stomaphis sinisalicis Zhang & Zhong, 1982 (Aphididae: Lachninae) is recognized for the first time in Korea, on Salix babylonica L., S. koreensis Anderss. and S. hulteni Floderus (Salicaceae).