dolichopodid fly with metallic legs dancing on wet mud

Size
Length: 3–8 mm
Lifespan
1–2 years
Diet
Predatory: adults feed on small insects including aphids, mites and fly larvae. Hunts on foliage using long legs to run quickly across leaves. Larvae also predatory, feeding on small invertebrates in soil and leaf litter.
Habitat
Sun-drenched broadleaf leaves, near streams and in garden shrubbery. The metallic jewels of the daytime foliage.
Range
Throughout North and South Islands in gardens, forests, grasslands and wetlands. Most common in lowland areas with abundant foliage for hunting and sunlit conditions.
Endemism
Native
Main Threats
Habitat loss from urban development and intensive agriculture. Pesticide use in gardens and farmland which kills both adults and their prey.
Population
Abundant throughout New Zealand. Easily recognised by brilliant metallic sheen and fast, sideways-scuttling movement on leaves.
Conservation Status
Not Threatened
A shimmering, metallic exoskeleton flashes in shades of iridescent green, copper and bronze. A fly that shines like a jewel. The long-legged fly is among the most aesthetically striking of all New Zealand dipterans. Unlike many of their scavenging relatives, these are high-energy predatory sprinters designed for a life of active hunting on the surface of broad leaves. A fly that hunts. Exceptionally long, stilt-like legs allow them to stand high above the leaf cuticle. This provides a superior vantage point from which to scan for smaller prey such as aphids, midges and thrips. When a target is sighted, they pounce with a sudden, explosive burst of speed. Specialised mouthparts consume their catch with remarkable efficiency. During courtship, the males, who often possess enlarged or brightly coloured front feet called tarsi, perform a complex, high-speed dance in front of the female. They wave their legs in rhythmic patterns to signal their fitness. This behaviour combines the delicate aesthetic of fine jewellery with the raw instincts of a cheetah. A fly that dances for love. The life cycle begins in damp soil or decaying wood. The larvae act as beneficial predators of other soil-dwelling invertebrates, making them an essential component of the vibrant canopy and the underlying forest floor. Not currently threatened, the long-legged fly serves as a vital indicator of a healthy, biodiverse garden or forest edge. The garden is sunny. The long-legged fly stands on a leaf, metallic green flashing, long legs stilt-like. It spots an aphid. It pounces. It eats. It does not know it is a jewel. It does not know it dances. It just wants to eat aphids. And shine while doing it.