Large sesame grass - Large sesame grass

This butterfly belongs to the order Lepidoptera, family Lycaenidae. In Japan, it is found in the southern part of the Oshima Peninsula in Hokkaido, and in the mountains of Honshu (Tohoku, Kanto, and Chubu), and is seen in valleys deep in the mountains. In foreign countries, it is found in the Korean Peninsula and Primorsky Krai in the Russian Federation. It is similar to the Japanese silverleaf, but is larger, with a wing span of about 40 mm. The underside of the hindwings is strongly gray-green-blue. It appears once a year, appearing from July to August, with the peak season being from late July to early August. The Japanese silverleaf lives in grasslands, but this species occurs in grasslands along rivers in forests in mountain valleys. The larvae feed on the flower spikes of the Japanese lily, which is a member of the Lamiaceae family. The fourth-instar larvae are brought into the nests of comb ants, and grow by feeding on the ant larvae. It overwinter as a larva.

[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。日本では北海道の渡島(おしま)半島南部、本州（東北、関東、中部）の山地に分布し、深山の渓谷にみられるチョウである。外国では朝鮮半島、ロシア連邦の沿海州に分布する。ゴマシジミに似ているが、より大形、はねの開張40ミリメートル内外。後ろばねの裏面は強く灰緑青色を帯びる。年1回発生し、7～8月に出現するが、7月下旬から8月上旬が最盛期。ゴマシジミは草原に生息するが、本種は山間渓谷の森林の川沿いの草地に発生する。幼虫の食草はシソ科のカメバヒキオコシ、クロバヒキオコシの花穂。4齢幼虫はクシケアリによってその巣中に連れ込まれ、アリの幼虫を食べて育つ。越冬態は幼虫である。

［白水　隆］

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