Asama Shijimi - Asama Shijimi

A butterfly belonging to the order Lepidoptera, family Lycaenidae. It is distributed in the mountains of Hokkaido, the Chubu region of Honshu, and the western Kanto region, and there are some significant differences in the size and color of the adults depending on the region. Until recently, the species found in Hokkaido were called Iburi Shijimi, those found in Kamikochi, Nagano Prefecture were called Yarigatake Shijimi, those found in Togakushiyama, Nagano Prefecture were called Togakushi Shijimi, and those found in the low mountain areas of the Chubu region were called Asama Shijimi, and they were often considered to be different species, but now they are all considered to be geographical variations of the same species. Outside of Japan, it is distributed in the Korean Peninsula, northeastern China, and eastern Siberia. The wingspan is about 30 mm, and the upper surface of the male's wings varies regionally from light blue to a dark indigo blue with a slight purple tinge. The upper surface of the female's wings is dark brown and has no blue scales. It appears once a year, from around mid-June in the low mountain areas and from July to August in the highlands. The larvae feed on legumes, Nandina bush clover, Astragalus membranaceus, Hepatica membranaceus, Momensuru, Ebirafuji, Kusafuji, Four-leaved bush clover, and Miyamataniwatashi. They overwinter in the egg form.

[Takashi Shiramizu]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

昆虫綱鱗翅(りんし)目シジミチョウ科に属するチョウ。北海道、本州の中部地方および関東地方西部の山地に分布し、地域により成虫の大きさや色彩にやや著しい差異がある。近年まで北海道産はイブリシジミ、長野県上高地産はヤリガタケシジミ、同県戸隠山(とがくしやま)産はトガクシシジミ、中部地方低山地産はアサマシジミとよばれ、それぞれ別種とされることが多かったが、現在ではすべて同一種の地理的変異として扱われている。日本以外では朝鮮半島、中国東北部、東シベリアに分布する。はねの開張は30ミリメートル内外、雄のはねの表は明るい青色からやや紫色を帯びた暗い青藍(せいらん)色まで地域的な変異がある。雌のはねの表は暗褐色で青色鱗はない。年1回発生し、低山地では6月中旬ごろから、高地では7～8月に出現する。幼虫の食草はマメ科植物、ナンテンハギ、シロウマオウギ、タイツリオウギ、イワオウギ、モメンズル、エビラフジ、クサフジ、ヨツバハギ、ミヤマタニワタシなどを食べる。卵態で越冬する。

［白水　隆］

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