march fly whose bite draws blood from stock and trampers

Size
Length: 8–12 mm, Weight: 0.1–0.3 g
Lifespan
1–2 years
Diet
Larvae feed on decaying organic matter in soil and leaf litter. Adults feed on nectar and are important pollinators of native flowers.
Habitat
Grasslands, forest margins, and gardens. Seasonal visitors that often appear in large, slow-moving swarms during spring and autumn.
Range
Found throughout the North and South Islands in forests, grasslands, and gardens. Most common in lowland areas with rich, organic soils and abundant flowers.
Endemism
Native
Main Threats
Habitat loss from forest clearance and conversion of grasslands to agriculture. Pesticide use. Drainage of wetlands reduces breeding habitat.
Population
Despite their name, they are often most visible in New Zealand during spring. They are famously clumsy flyers, often seen drifting lazily through the air in pairs.
Conservation Status
Not Threatened
The gentle drifter of the New Zealand meadow is defined by a sturdy, often densely hairy anatomy and a distinctive, slow-motion flight style. These flies are easily recognised by their unique dangling leg posture while airborne, which creates an awkward, leggy silhouette as they appear to struggle against an invisible current. This laboured flight distinguishes them from the high-speed aerial acrobatics of hoverflies or houseflies. Males frequently possess massive, divided compound eyes that occupy nearly the entire head, a specialised sensory adaptation for locating females. The life cycle begins in the cool, damp earth where the larvae operate as communal feeders. These gregarious larvae live in dense clusters within the soil or leaf litter, working collectively to break down decaying organic matter and roots. That process facilitates nutrient cycling. Upon emerging as adults, they transition into important pollinators of native flowers, moving lethargically from bloom to bloom. They represent a state of leisured abundance, illustrating a survival strategy that relies on sheer seasonal numbers rather than individual speed. While they are currently not threatened, march flies are a vital component of the local food web. They serve as a seasonal protein boom for insectivorous birds such as the fantail and various freshwater fish when they succumb to the water's surface. Protecting these flies is largely a matter of maintaining healthy soil structures and avoiding heavy use of subterranean pesticides. To observe a march fly drifting lazily through a sun-drenched paddock is to witness a survivor that has mastered the art of lazy abundance.