Tawny Coster Acraea terpsicore

This butterfly has a neat trick: its wings are genuinely tough and leathery — thicker and more durable than almost any other butterfly — and it is so unpalatable that nearly every insect predator avoids it entirely. That freedom lets it adopt a slow, fluttery, almost carefree flight style that would be suicidal for a tastier species. It has also been spreading aggressively into Australia in recent years — a remarkable feat for a butterfly traditionally associated with South and Southeast Asian grasslands. It's one of only two Indian representatives of a tribe that is otherwise almost entirely African in origin.