Ceylon birdwing  (Troides darsius)

Listed on Appendix II of CITES (1).

The Ceylon birdwing is one of the largest butterflies of Sri Lanka (2). Like most other Troides birdwings, the male is adorned with bright golden-yellow markings on the hindwings, which contrast starkly with the velvety black forewings and interjecting black veins (2). The female is larger than the male, and has a different arrangement of yellow markings on the hindwing, and pale stripes on the forewing (2) (3).

Endemic to Sri Lanka (4).

Occasionally observed in lowland cities (5), this species survives today mainly in its primary habitat of thinly wooded mountain forests, throughout the island with the exception of the far north (4). The Ceylon birdwing has been recorded from sea-level up to an elevation of 2,000 metres, but is now less frequently seen in the lowlands (5).

The Ceylon birdwing is most active during the morning and early afternoon (3) (5). The butterfly feeds on the nectar of flowers such as Hibiscus, Poinciana (Caesalpinia pulcherrima) and Bougainvillea (3), and the larvae found on the leaves of Aristolochia plants (3) (6).

Orange-yellow eggs are laid singly on the young leaves and shoots of the Aristolochia food plants, which are then voraciously devoured by the young caterpillars after hatching (3) (6). Feeding upon these plants also serves as a defensive mechanism as they contain certain chemicals that make the caterpillars toxic and therefore unpalatable to most predators (7). The caterpillars eventually pupate and undergo metamorphosis into adult butterflies, and maintain these toxic chemicals in their tissues into adulthood (7). The chrysalis of this species is dark brownish-yellow, or greenish-yellow in some individuals, and its leaf-like appearance helps camouflage it amongst the vegetation from potential predators (3). Troides birdwings typically pupate on the twigs or stems of plants close to the larval food plant or on the food plant itself (3).

The principal threat to Troides butterflies is deforestation (6). The Ceylon birdwing is under considerable pressure from an expanding and encroaching human population, and from habitat destruction associated with human development (4).

The Ceylon birdwing is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning that any international trade in this species should be carefully monitored (1). However, more needs to be done to help preserve its fragile habitat, including the Aristolochia food plants on which the larvae rely, if the long-term future of this stunning native butterfly is to be safeguarded (6).

View information on this species at the UNEP World Conservation Monitoring Centre.