The bathroom is not where most people expect to find wildlife. The drain fly does not care. The fuzzy specialist of the film. The drain fly, often called the moth fly, is defined by a dense coating of fine, water-repellent hairs that give it a deceptively cuddly or moth-like appearance. This unique anatomy is a functional adaptation for their preferred habitat: the gelatinous biofilm of bacteria and organic matter that accumulates inside drains, septic tanks and damp plumbing fixtures. A fly that lives where no one wants to look. Far from being mere pests, they operate as the janitors of the plumbing. Their legless, leathery larvae are specialised to graze on the thick sludge and microbial gunk that would otherwise clog human water systems. By consuming this organic buildup, they play a critical role in nutrient recycling within the highly modified environments of modern infrastructure. A fly that cleans the pipes. These insects are notoriously poor flyers, possessing broad leaf-shaped wings better suited for short erratic hops or scuttling along wet surfaces than for sustained aerial travel. This limited mobility keeps them closely tied to their larval nurseries, making them a definitive sign of domestic microbiology. As an introduced species in New Zealand, they primarily occupy human-modified environments and do not pose a threat to native forest or aquatic biodiversity. While a sudden swarm in a bathroom can indicate a slow-moving drain or a leak in a pipe, they do not bite or transmit diseases to humans. The shower drain backs up. A dozen fuzzy flies emerge, fluttering weakly, scuttling across the tiles. They are not elegant. They are not beautiful. But they are doing a job that no one else wants. And the pipes stay clear. No one thanks the drain flies. They do not expect thanks.