About Erasmia pulchella Hope, 1840
Erasmia pulchella Hope, 1840 is a moth species belonging to the burnet moth family Zygaenidae. It is a moderately large moth, with a wingspan ranging from 70–80 millimetres (2.8–3.1 in). Its wings are covered in bright, iridescent patterns that act as aposematic deterrence to predators. The base wing color is turquoise, mottled with black and white markings, and a reddish-orange band crosses through the forewing pattern. The outer edge of both forewings and hindwings is black, while hindwing pattern varies between subspecies. This species occurs across a broad geographic range and is highly variable across its distribution: mainland Japanese subspecies are the darkest, while the Okinawa subspecies has a brighter blue color. Among Chalcosiine moths, a study by Yen Shen-Horn et al. postulates that E. pulchella shows the greatest degree of wing maculation and zonation of all its relatives. Multiple observers have called E. pulchella one of the most beautiful moth species, the most beautiful moth in Japan, and the most beautiful moth of Southern Japan. Originally describing the species, Hope noted it is certainly one of the most beautiful Lepidoptera, and one of the most lovely in coloring of all Lepidoptera. Due to its striking wing coloration, this moth has often been harvested to make jewelry, both historically and in modern times. Its aposematic coloration reflects the species' toxic nature: its body contains hydrogen cyanide across all life stages. As an additional anti-predator defense, adult moths can exude noxious foam from their heads to deter predators. E. pulchella is diurnal, and adults visit flowers during the day to drink nectar with their proboscis. When at rest, the moth holds its forewings closed over its body, completely covering the hindwings. Erasmia pulchella is distributed across Southern and Eastern Asia, ranging from Northern India through Myanmar, Laos, Thailand, Vietnam, and China, extending east as far as Taiwan and Japan. In Japan, four subspecies are recognized, with a distribution stretching south to the Ryukyu Islands; the easternmost limit of the species' range in Japan is the Kii Peninsula. The moth's distribution in Japan is limited to the range of its host plant, Helicia cochinchinensis, which does not extend past the Tōkai region, and the moth rarely strays far from this host plant. Currently recognized subspecies include: subspecies nipponica, found on Honshu, Shikoku, and Kyushu on the Japanese mainland; subspecies fritzei, found on Amami Ōshima and in Okinawa Prefecture; subspecies kumageana, found on Yakushima and Tanegashima; subspecies sakishimana, endemic to the Yaeyama Islands; the nominate subspecies pulchella, found in Northern India; subspecies hobsoni, found on the island of Taiwan; and subspecies chinensis, described from the mountains of Myanmar by Adalbert Seitz and additionally found in Vietnam. Three taxa previously treated as subspecies are no longer classified as such: former subspecies hainana occurs on Hainan Island, China; former subspecies cyanea was described from Hong Kong; and former subspecies sangaica occurs in Northern China and Southern Japan.
