Hestina assimilis, the red ring skirt, is a species of butterfly in the family Nymphalidae found in Asia. It is generally of large size. There are several subspecies: H. a. assimilis, H. a. formosana (Moore, H. a. shirakii (Shirozu, 1955), and H. a. f. nigrivena (Leech)[1]
H. assimilis is found from eastern Tibet to most all of China, in Hong Kong and in Korea.[2] Originally, this butterfly inhabited the subtropical regions of southern China, Taiwan, and Japan south of Kagoshima Prefecture, but now, due to global warming, its distribution range in the Japanese archipelago has expanded to the north, and it has even appeared in the Kanto region, in the central part of Honshu, Japan. It is now commonly seen in urban areas of Kanagawa, Tokyo, and Saitama Prefectures in Japan, and its breeding range is expanding.
H. assimilis often uses its long proboscis to probe in muddy soil or gravel to get the moisture it needs.[3] The male is strongly territorial, always staying in high positions to defend its territory.