Helophilus seelandicus (Gmelin, 1790)

REDUCED_NZ-Ento-Soc-Insect-Playing-Cards_Hover-fly REDCommon names: Three lined hover fly, Ngaro tara

Order: Diptera     Family: Syrphidae

Size: 15 mm

Three distinctive black stripes on the adult flies’ thorax gives this species its common name: the three-lined hover fly. Often hover flies are mistakenly for bees because of their stripes, but this is just a clever form of mimicry which allows this harmless fly to avoid predators. A hover fly can be distinguished from a bee by counting the number of wings; flies have one pair of wings and bees have two. Like bees, however, hover flies are important pollinators and are welcome guests in the garden.

The larvae of the three lined hover fly, and other species in this group, are called rat-tailed maggots because they have long breathing tubes that extends from their body. The tube acts like a tiny little snorkel, and allows the fly larvae to live in oxygen-deficient water, such as those that are polluted with dairy-farm effluent or sewage. Although the presence of hover fly larvae is a useful sign that a waterway is polluted, these conditions are well-suited to the larvae which feed on the decaying organic matter.


Moore, S. (2012). Rat Tail Maggots (SYRPHIDAE : SYRPHIDAE ). Retrieved from http://www.landcareresearch.co.nz/resources/identification/animals/freshwater-invertebrates/guide/no-jointed-legs2/true-fly-larvae/other/rat-tail-maggots/

Threelined hoverfly. (created 2012). Retrieved from https://www.landcareresearch.co.nz/resources/identification/animals/bug-id/what-is-this-bug/what-did-that/makes-a-noise/threelined-hoverfly/