The genus Illinoia is originally distributing in North America, few species found in other continents as exotics with the introduction of their hosts as ornamental plants and weeds. Recently, we confirmed two Illinoia species in Korea as the first record of this genus in the Eastern Part of Palaearctic: Illinoia goldamaryae (Knowlton 1938) on Erigeron sp. (Asteraceae) and I. liriodendri (Monell 1879) on Liriodendron tulipifera (Magnoliaceae). Two exotic aphids are illustrated, diagnosed, and discussed for their host plants, distribution, etc.