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

Chaoboridae Chaoborinae

Major Group: Insecta
Subfamily: Chaoborinae
This family is represented in Australia by a single subfamily, Chaoborinae.

Descriptive Features:

  • head capsule complete, not retractile into thorax
  • antenna prehensile, bearing numerous spines
  • mandibles usually with several teeth
  • air sacs present in thoracic and 7th abdominal segments
  • abdomen 9-segmented
  • prolegs absent
  • Total length: up to 15mm


      Taxonomic Checklist: Genera
      Australomochlonyx nitidus Freeman
      Chaoborus (5 species)
      Promochlonyx australiensis Ferguson

      Distribution: Australia wide

      Sensitivity Rating: SIGNAL grade 2

      Functional Feeding Group: predators, filtering collectors


      Hindmarsh Island in Lake Alexandrina, SA

      Ecology: Instream habitat: Chaoborus larvae are usually found in sunlit lakes and reservoirs, but may also be collected in rivers with side-pools and backwaters. Atypically, several larvae have been found amongst debris in a fast current (possibly because they were protected from the flow). Promochlonyx australiensis larvae are found in pools in freshwater swamps or on swampy land. Australomochlonyx nitidus larvae are found in pools in slow-flowing creeks, seepages, or swampy ground.
      Feeding ecology:Larvae of Chaoborus and Promochlonyx australiensis are predacious upon small aquatic life such as Cladocera, insect larvae and other chaoborid larvae. Australomochlonyx nitidus larvae are filter feeders with large mandibular fans that strain micro-organisms from the water.
      Habit: Chaoborus larvae are commonly known as ‘phantom midges’ due to the transparency of their abdomens. They have benthic and pelagic phases. The benthic phase moves through the water by lashing motions. The pelagic phase lie freely suspended at certain levels in the open water. All chaoborid larvae in Australia have two pairs of air-sacs that function as hydrostatic organs to allow them to ‘balance’, usually about mid-depth. Chaoborus adults can be minor pests around lights and larvae sometimes block filtration plants in water supplies. The larvae are nocturnal. They stay near the bottom of the waterbody by day and rise near the surface at night.
      Life history: Chaoborus adults are usually found near water in spring to midsummer.


      Information Sources: Colless & McAlpine 1991, Colless 1986, Hawking & Smith 1997, Bugledich 1997, Williams 1980
      Key to Genera: Colless 1986 (larvae & pupae, including genera no longer in Chaoboridae)
      Key to Species: Colless 1986 (larvae & pupae - Chaobrus)