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


Major Group: Insecta
Order: Diptera
Family: Blephariceridae 

Descriptive Features:

  • body dorso-ventrally flattened and distinctly lobed
  • anterior (cephalic) division consists of head, thorax and 1st abdominal segment fused
  • 5 posterior lobes represent abdominal segments
  • terminal division consists of abdominal segments 7-10 fused
  • ventral surface of 6 segments bearing sucking disc
  • Total length: up to 13mm
  • Taxonomic Checklist: Subfamilies

    Distribution: Vic, Qld, ACT, NSW, Tas

    Sensitivity Rating: SIGNAL grade 10

    Functional Feeding Group: scrapers

    Ecology: Adult blepharicerids are called ‘net-veined midges’ because of the fine network of lines on their wings. The present range of Blephariceridae is diminishing as they are sensitive to pollution, movement of sand or silt and are unable to survive in streams which have abruptly changing water levels e.g. hydroelectricity production, or unseasonable changes in flow conditions e.g. irrigation.
    Instream habitat: Larvae and pupae are only found in swiftly flowing waters on submerged stones, even within the splash-zone of cascades. Adults are found close to larval habitats.
    Feeding ecology: Larvae use specialised scraping mouthparts to feed on microscopic algae. They tend to avoid the larger algae that accumulate in nutrient rich waters.
    Habit: Larvae often cluster in small groups by adhering to the rock surfaces with their suckers. Pupae also attach to the substrata but remain fixed in one position by lateral adhesive areas. Some adults congregate on rocks close to water, but others are more elusive and rarely seen.
    Life history: Eggs are laid on smooth rocks and boulders alongside or within fast flowing streams, usually as the water level is dropping. When the water level rises again, hatching takes place and larvae adhere, in clusters, to the surfaces of the substrata. There are four larval instars. Pupation is rapid so pupae and adults are usually present at the same time of year. Pupae tent to be found in the thin water film at the edge of the flow rather than within the main flow. Adults do not swarm instead they cluster underneath rocks and fallen logs close to their emergence sites.
    The life cycles of Australian Blephariceridae can be grouped into types that are distinguished by temperature cues and different speeds of larval development. The first three types spend a greater time in the egg stage and are absent from the stream for a distinct period of the year. They are univoltine – one generation per year.
    WINTER TYPE: Larvae start to hatch in March-April. By June larvae are abundant and most are in the final instar. During the coldest period of the year there is little larval growth or pupation. In September, when overall numbers are highest, larvae pupate in large numbers then remain abundant until early November. Adults are also prevalent in October-November. These species are not found in the stream from December to February.
    EARLY-SUMMER TYPE: Larvae hatch in winter from July onwards and growth is slow but steady. Pupation begins in October then pupae are abundant in November-December, when overall numbers are highest. Adults are also prevalent in December-January. These species disappear from the stream during hottest part of year, from late January onwards.
    LATE-SUMMER TYPE: Larvae start to hatch in November. They develop fast and pupae are dominant in December. Pupae are abundant during the warmest part of the year, until emerging in January but the flight period may extend until February. These species disappear from the stream during the colder months, from late March onwards.
    Perennial types usually have different stages of two generations present at the same time and the species do not disappear from the stream for a period of time. These species may have either one or several generations within the span of a year.
    UNIVOLTINE PERENNIAL TYPE: Adults fly in the warm summer months. First instar larvae appear whilst pupae from the previous generation are still present, as late as June. By April, most larvae are third instar with instar three and four dominating until spring. In October, pupation and flight begins again.
    MULTIVOLTINE PERENNIAL TYPE: Larvae are found during most of the year. Pupae appear at the height of summer then dominate during autumn and winter. In January, young larvae and pupae are present together. Adults usually have two flight periods.
    Information Sources: Zwick 1977, 1981, 1998, 2006, Bugledich 1999 & 1997, Colless & McAlpine 1991, Williams 1980, Hawking & Smith 1997, Gooderham & Tsyrlin 2002
    Key to Subfamilies: Zwick 1977 (pupae)
     More ›››  key to sub families