water boatman sculling across the pond with oar-like legs
- Size
- Length: 5–10 mm
- Lifespan
- 6–12 months
- Diet
- Omnivorous: feeds on algae, detritus and small aquatic insects. Swims using long, oar-like hind legs which row through the water. Often swims upside down near water surface. Does not bite humans.
- Habitat
- Ponds, lakes and slow-moving streams with abundant aquatic vegetation. The rowers of the surface film, gliding effortlessly just below the water line.
- Range
- Throughout North and South Islands in ponds, lakes and slow-moving streams with abundant aquatic vegetation. Most common in lowland areas with permanent water bodies and diverse aquatic plant communities.
- Endemism
- Native
- Main Threats
- Water pollution from agricultural runoff and urban development. Habitat loss from drainage of ponds and wetlands. Predation by introduced fish species which eat adults and nymphs.
- Population
- Water boatmen are common and widespread in New Zealand. Resilient creatures, tolerant of range of water conditions, though thrive best in unpolluted, plant-rich environments. Crucial food source for fish and water birds.
- Conservation Status
- Not Threatened
The oar-smith of the pond. A bug that rows across the surface.
Named for its rowing hind legs, which move in a synchronised, swimming motion reminiscent of a tiny crew team, the water boatman navigates the underwater world with surprising grace. It spends most of its time hanging upside down from the surface tension, breathing through a bubble of air trapped against its body like a silver diving suit. It is a master of buoyancy, adjusting the size of its air bubble to sink or rise at will. A bug that carries its own air tank.
Despite their peaceful appearance, many water boatmen are opportunistic predators, snatching mosquito larvae and small invertebrates with their front legs. Some species are even capable of producing sound by rubbing their genitals against their abdomen, a stridulation that creates a high-pitched chirp audible above the water. It is a romantic serenade performed in the dark, a tiny violin concert for potential mates. A bug that sings with its private parts.
They are often confused with backswimmers, which swim right-side up and bite aggressively. The water boatman, by contrast, is generally gentle and feeds on detritus and algae, making it a beneficial resident of the garden pond. They are the quiet commuters of the aquatic world, shuttling back and forth in the weeds, unnoticed until scooped up and their faint, squeaky protest is heard.
To watch a water boatman row across the surface is to witness a tiny rower on an endless pond. The pond is still. The boatman rows, legs moving in sync, silver bubble gleaming. It does not know it is a marvel. It does not know it sings with its genitals.
It just rows. That is what boatmen do.