A colleague of mine planted native Aristolochia vines a few years ago in the hope of attracting more butterflies to her garden. It seems her efforts finally paid off with the arrival of stunning Cairns Birdwing Butterflies (Ornithoptera euphorion) earlier this year!
Found along northeastern Australia from Mackay to Cooktown, the Cairns Birdwing is Australia’s largest endemic butterfly. The females’ wingspan can measure a whopping 18cm, and they’re easily recognized thanks to their vivid coloration. I think their highly adapted lifecycle is their most fascinating attribute…
They are fussy butterflies who lay eggs on native rainforest Pipe Vines (Aristolochia tagala and Pararistolochia deltantha). Females find the ideal vine using chemical receptors in their legs and abdomen to ‘sense’ tender, caterpillar-friendly leaves. Newly hatched caterpillars eat their own nutritious egg shell, and will even eat other caterpillars if times are tough. Caterpillars are brightly coloured to ward off predators, and store toxins absorbed from Pipe Vines so attackers won’t make the same mistake twice!
When caterpillars are almost ready to pupate they ringbark their vine. Although leaves droop from water loss, the flow of nutrients is concentrated so the caterpillar gets a more nutritious meal before pupation. Pupation occurs in a cleverly camouflaged cocoon, which resembles a dead, dried leaf.
As soon as adult butterflies hatch the race is on to mate, as they only live for 4 – 5 weeks. Males are extremely territorial, performing early morning patrols and competing with other males to find fresh, newly hatched females. Courtship can be lengthy (up to 36 hours) and aggressive, and apparently the female slips the male a sedative to ensure he behaves himself!
The species was once under threat due to wide-scale clearance of its native rainforest habitat, and the spread of exotic vines including Dutchman’s Pipe (Aristolochia elegans). A. elegans closely resembles the native A. tagala vine, and is lethal to the butterflies in their larval stage.
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