If you are walking through a North Island forest at dusk and something the size of a small bird hits you in the face with the structural integrity of a damp tea towel, you have likely just met a pūriri moth. This is New Zealand's undisputed heavyweight champion of the air. With a wingspan that can reach fifteen centimetres, they are a startling sight. Vibrant forest-green wings patterned with delicate, lichen-like markings make them invisible when resting on a mossy trunk. They are the jumbos of the insect world, but their impressive adult form is merely a frantic, week-long finale to a very long and very hidden life story. The biography of a pūriri moth begins in the dirt. A female can scatter up to two thousand eggs onto the forest floor, a biological spray and pray tactic. The tiny caterpillars that survive must find a piece of decaying wood to start their journey, eventually migrating to a live tree, usually a pūriri or a marbleleaf. Here, they become the engineers of the trunk. They bore a characteristic seven-shaped tunnel deep into the heartwood, which they cap with a camouflaged web of silk and chewed bark. They spend up to five years in this dark, wooden bunker, feeding on the nutritious callous tissue the tree grows in response to the injury. They are the ultimate long-term tenants, growing to the size of a man's finger before they finally decide it is time to see the sky. When the transformation is complete, the adult moth emerges for a short and fast life that borders on the tragic. Like the glowworm fly, the adult pūriri moth has no mouth. It cannot eat. It cannot drink. It exists on the fat reserves it accumulated during its five-year tenure inside the tree. It has roughly seven to nine days to find a mate, lay its eggs, and then die of exhaustion. That creates a desperate, high-stakes energy to their flight. They are notoriously clumsy fliers, drawn to the moon of streetlights and porch lamps, where they often end their lives flapping helplessly against a cold lightbulb or falling prey to a waiting cat. Despite their size, pūriri moths are remarkably gentle. To see one in the wild is a rare gift, a glimpse of a five-year project finally taking wing for a few nights of green, ghostly glory.