Troides darsius, the Sri Lankan birdwing, is a species of birdwing butterfly found in Sri Lanka. It is the largest butterfly on the island. Among the largest and most gaudy of the Ceylon Lepidoptera is the great black and yellow butterfly (Ornithoptera darsius, Gray); the upper wings, of which measure six inches (15 cm) across, are of deep velvet black, the lower, ornamented by large particles of satiny yellow, through which the sunlight passes, and few insects can compare with it in beauty, as it hovers over the flowers of the heliotrope, which furnish the favourite food of the perfect fly, although the caterpillar feeds on the aristolochia and the betel leaf and suspends its chrysalis from its drooping tendrils.