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

Diptera (flies)

Major Group: Insecta
Order: Diptera

Descriptive Features:

  • head sclerotized, may be retractile or not retractile
  • mouthparts may be conspicuous or inconspicuous
  • if conspicuous, mouthparts biting with mandible and maxilla developed for grasping and chewing
  • wings and wing pads absent
  • caudal filaments, caudal gills and caudal processes absent
  • 1 pair of unjointed prolegs on thorax present or absent
  • posterior end of body with at least 1 of - or a combination of, - gills, hair brushes, sucker or breathing tube
  • animal may be in a soft, open- ended tube but never completely enclosed
  • total length:
  • head sclerotized, may be retractile or not retractile
  • mouthparts inconspicuous
  • animal usually, but not always, completely enclosed in a case
  • wings may be developing
  • prolegs absent
  • total length:
  • Taxonomic Checklist:





    Distribution: Australia wide

    Sensitivity Rating: SIGNAL grade 3

    Functional Feeding Group: predators, scrapers, shredders, gathering collectors, filtering collectors

    Ecology: Instream habitat: Dipteran species can be collected in the whole range of habitats from the most pristine environments to the most polluted, from stagnant to fast flowing lotic waters, from freshwaters to saline waters. Larvae and pupae are found amongst organic debris, aquatic vegetation, snag habitats, fine sediments, sand, mud, gravel, cobbles or bedrock. They may be closely associated with, and sometimes restricted to, any of the aquatic zones - water surface, water column, main flow, littoral, benthic, interstitial and hygropetric zones.
    Feeding ecology: Dipteran larvae are represented in all the functional feeding groups. Some species are restricted to one particular feeding mode and have specialised mouthparts whilst other species are opportunistic and factors including larval size, maturity, food quality, sediment composition and seasonal or environmental change can influence their feeding behaviour. Gathering collectors feed on organic detritus deposited on submerged substrata. Filtering collectors feed on suspended diatoms and fine particulate detritus filtered from the water column. Scrapers use well-developed mandibles to scrape algae, bacteria, fungi and diatoms from the surface of rocks, wood and other submerged objects. Shredders use chewing and boring to feed on living macrophytes, submerged wood, macro-algae or leaf litter. Predators prey on other invertebrates, including their own species. Generally pupae do not feed. Many adults feed on either, or both, animal and human blood as well as plant nectar and honeydew (the sweet liquid excreted by other plant feeding insects), however some adults do not feed.
    Habit: Few Australian dipteran species are well studied but it is known that a wide variety of habits are demonstrated, some of which are typical at the family level.
    Life history: The biology of some dipteran families is not known so the following information is a combination of northern hemisphere studies and Australian studies. Some dipteran females require a blood meal before or after mating to mature the eggs. Eggs may be laid in or near to the larval habitats. Some eggs are dependant on continuous water contact to survive where others can withstand desiccation and hatching beings only after inundation. Eggs can be laid singularly or in adhesive clusters or gelatinous masses of up to 700 eggs. Length of the egg phase is variable, from two days to ten months, with those eggs able to withstand desiccation waiting for long periods until the water level rises and hatching takes place. There are four to nine larval instars, most commonly four. The habits and feeding ecology of a particular species may change as the larva passes through the instars. The length of the larval phase varies according to species, region and seasonal temperatures, from four days to almost one year. Final instar larvae often leave the water to pupate in damp riparian litter or soil, but not always; this seems to be typical at the family level. Pupation can occur within a modified final larval skin or a silken cocoon. The pupal phase is usually short relative to the larval phase, from a few hours to four weeks. Dipterans are present as adults, larvae and pupae throughout the year with peaks in adult emergence and presence over the warmer months, however within a species or even a family the timing of emergence is specific. Adults may or may not swarm depending upon the family, with those that do swarm often displaying mass emergence over a short time period. Mating can occur shortly after emergence or just before oviposition and takes place in flight or while landed but is usually done near to water. Adults are typically short-lived, from one or two days up to a few weeks. Dipteran species may be univoltine (one generation per year), bivoltine (two generations per year), multivoltine (several generations per year) or semivoltine (more than one year to complete a generation). The number of generations per year is largely determined by temperature, either the seasonal changes of temperature or regional differences in temperature, but can also be species dependant. Low temperatures delay development and tropical temperatures speed development.
    Information Sources: Colless & McAlpine 1991, Bugledich 1997, 1999, Cranston various, Elliot 2005, Evenhius 2007,  Keiper et al. 2002, Williams 1980, Gooderham & Tsyrlin 2002, Hawking & Smith 1997 and information sources listed on family pages 
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