Winter brings the rain. The soil softens. It is in this wet, grey season that the Puriri Moth Fungus appears. It does not shout. It does not demand attention. A slender, black stalk rises from the ground, no thicker than a matchstick. It is topped with a fertile head, where spores are produced. This is not a plant. It is the final stage of a parasitic relationship. Beneath the soil, the fungus has consumed the larva of the puriri moth, Aenetus virescens. The larva is dead, but its body remains intact, a hollow shell filled with white mycelium. The fungus takes control. It directs the larva to burrow close to the surface. Then, it stops. It waits for the right moment. The habitat is specific. The Puriri Moth Fungus thrives in the soil beneath puriri trees and other native hardwoods. It is found throughout New Zealand, from the northern forests to the southern beech lands. It fruits in winter and spring, often after heavy rain. It is not picky about its host, though it prefers the large larvae of the puriri moth. Its presence is a sign of a healthy, functioning ecosystem. Where it grows, the balance between predator and prey is maintained. It is an indicator species, a biological signal that the soil is alive with activity. This fungus is parasitic. It does not decompose dead wood or leaf litter. Instead, it feeds on living tissue, specifically the larvae of the puriri moth. In doing so, it regulates moth populations. It is a natural check on abundance. Without it, puriri moth numbers might surge, affecting the trees they feed on. The fungus enters the larva through the skin. It grows inside, consuming the soft tissue. The larva dies, but its exoskeleton remains intact. The fungus takes control. It directs the larva to remain in place. Then, it stops. It waits for the right moment. The fruiting body is a slender, black stalk that emerges from the head of the buried larva. It rises through the soil, breaking the surface like a thin, dark needle. The stalk is topped with a fertile head, where spores are produced. It is small, rarely exceeding five centimetres in height. It is easily overlooked, blending into the dark forest floor. It appears in late winter or spring, when the puriri moth larvae are most active. Threats are minimal. The species is widespread but elusive. However, it is sensitive to changes in soil structure. Logging, fire, or heavy grazing can disrupt the delicate mycelial networks beneath the forest floor. Compacted soil makes it difficult for the fruiting bodies to emerge. Recovery is slow. The fungi wait for the conditions to return. They do not rush. It carries on.