Gyrinus is known as the “Whirlygig beetle” which reflects the chaotic swimming motion of the adults on the water surface. The streamlined adults have distinctive eyes divided into halves (one looking upwards and one looking downwards). The larvae superficially resemble skinny Berosus larvae, having tentacle-like gills along the sides of the abdomen.
Gyrinus are infrequently recorded but they are most likely to be found in ponds, lakes and wetlands in the North Island.
Gyrinid beetles are predators, feeding on other freshwater invertebrates.
The presence of gyrinids is more likely to be a reflection of pond, lake or wetland habitats rather than any particular water quality conditions. They have not been assigned any tolerance values.