Butterflies
Red ring skirt / Hestina assimilis / Akaboshi go-madara / アカボシゴマダラ
These medium-sized butterflies found on Amami-Oshima are a subspecies of the red ring skirt found all over Asia, from Tibet and Vietnam to the Korean Peninsula and mainland Japan. Its wings, which reach lengths up to 53 millimeters, are black with white dots and stripes, and the hind wings are black with red ovals. (The other subspecies tend to have larger white areas on the wings.) The male is extremely territorial. The eggs are small, a little over 1 millimeter in diameter, and the larva is green with a dark-brown or black head that turns green after molting. While these butterflies are considered native to Amami-Oshima, the red ring skirt found in mainland Japan is considered an invasive species artificially introduced from the Asian continent.
Ryukyu blue glassy tiger / Ideopsis similis / Ryukyu asagi-madara / リュウキュウアサギマダラ
This medium-sized butterfly, endemic to Amami-Oshima, is a different genus from the chestnut tiger butterfly found throughout Asia. The wings of both males and females have a similar pattern of a light-blue background with dark-brown or black stripes. The wingspan can reach 7 centimeters. The larva feeds on plants from the dogbane family, so the butterflies are toxic and unafraid of predators. From December to February, they can be seen wintering in large groups in coastal forest areas and valleys protected from the wind. Below 15°C they become almost immobile, perching in masses on dead branches and vines.
