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 Major Groups | Insecta (insects) | Diptera (true flies) | Syrphidae

Syrphidae Eristalinae

Major Group: Insecta
Subfamily: Eristalinae
Genus: Eristalis
Aquatic species of Syrphidae in Australia are represented by a single genus, Eristalis.

Descriptive Features:

  • posterior spiracles close together on a fused process - a short to long retractile tube
  • head capsule incomplete, reduced in size and structure, without externally visible sclerotization, retractile into thorax
  • maxillary palps and antenna small or absent
  • cephalic structure a "cephalopharyngeal" skeleton 
  • mandibles usually with hooked apical tooth and lacking inner teeth, operating in ventral plane
  • abdomen 8-segmented
  • Total length: up to 30mm including tube

      Eristalis larva


      Eristalis pupa

      Taxonomic Checklist: Species
      tenax Linnaeus
      ?Eristalis calida Walker
      ?Eristalis dubia Macquart

      Distribution: Australia wide

      Sensitivity Rating: SIGNAL grade 2

      Functional Feeding Group: gathering collectors


      sewage outflow at Wonga Wetlands, Albury NSW

      Ecology: Instream habitat: Eristalis larvae occur in still and slow-flowing waters, often within highly polluted or low oxygen environments such as sewage. They are usually found in the sediment of shallow waters.
      Feeding ecology: Larvae are gathering collectors feeding on animal and plant tissue in the sediment.
      Habit: Eristalis larvae are commonly known as ‘rat-tailed maggots’ due to the telescopic breathing tube at the posterior end of the abdomen. This extendable ‘snorkel’ can stretch to the surface allowing syrphid larvae to breathe and survive in putrid water that lacks oxygen. Syrphid adults are swift fliers that typically hover, apparently motionless, in the air, giving rise to the common name of ‘hover-fly’.
      Life history: Adult hoverflies mate near water in spring then the female lays her eggs singularly in shallow water. Eggs hatch after a few days. Larvae pass through a number of instars before they pupate. Pupation occurs during summer when the final instar larva crawls out of the water by twisting its body to move across the soil. The last larval skin forms the pupal cell. The adult breaks out of the pupal skin after approximately three weeks and flies away.


      Information Sources: Colless & McAlpine 1991, Hawking & Smith 1997, Gooderham & Tsyrlin 2002, Evenhuis 2008, Wade et al. 2004
      Key to Species: none