It's spectacularly spiky and delivers a painful – or even deadly – sting. Why are a team of conservationists growing and planting up Orokonui Ecosanctuary near Dunedin with more and more native tree nettle, ongaonga? It's all because of a pretty little pollinator called the kahukura, or red admiral butterfly, and its prickly preferences. Claire Concannon visits Orokonui to learn more about the ongaonga-kahukura relationship, as well as new research investigating whether these native butterflies are the victims of a sneaky ecological 'trap'.