ツシマウラボシシジミの生活史

Pithecops fulgens (Polyommatinae) occurs in Assam, Formosa and Japan. In our country this species is distributed only in the island of Tsushima. Little is known about the life-history, therefore the authors have researched it as well as the zoo-geographical aspect since 1973, in cooperation with the Survey on Tsushima Biological Researches by the Nagasaki Biological Society. The following results have so far been obtained. 1. This species is only found from the north-western parts of the Tsushima island, extending northwards to Kawachi and Izmi of Kamitsushima-cho and southwards to Mine and Okubo of Mine-cho. It is absent from the east coastal areas of there. 2. It inhabits in the darker, moist cedar forests, where the following larval food-plants (Leguminosae) grow abundantly. Demodium oldhamii Oliver D. laxum DC. D. osphyllum DC. D. fallax Schindl. D. fallax Schindi. var dilatatum Nakai D. podocarpum DC. 3. The butterfly is on the wing from early May to the middle of October. There are five broods in the year. The spring form is larger than the summer one. It visits various flowers in bloom, which serve nectar, and occasionally sucks water on muddy ground. 4. The egg is laid singly on a new bud of the larval food-plants in spring, and siso on the petal in summer. The larva hatches three day after oviposition, and feeds the buds or petals. It may eat the leaves, but does not remain there. 5. The last instar larva makes its nest before pupating. In spring, it bits partially the underside of the petiole, binds up two of the three drooping leaflets with silk, and then pupates on the silk-lined main vein near the base directing the head toward the leaflet-apex. In July and August, the last instar larva feeds the petals. When fully grown, it moves down the stem and makes the nest on the undersurface of the lower leaflet directing the head in generl toward the leaflet-tip. Some larvae pupate on the spikelet downwards. The larval stage is approximately 17 days. In autumn, the last instar larva makes the nest with leaflets, which falls down in late autumn naturally. It passes the winter and pupates in the nest in April without having any food after hibernation. The pupal stage ranges from 8 to 10 days. 6. The nesting behaviour of P. fulgens seems apparently to be similar to that of the first instar larva of Arhopalini and to the self-hiding behaviour of Theclini, but the nature is supposed to be essentially different.