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March flies


  • also called Horse flies, March flies (Tabanids) of which there are 20 genera and 227 species in Australia
  • they are large (6-25mm), robust flies with large eyes
  • they are widespread throughout Australia, but preferring regions near moist soils
  • the adult females will target most warm blooded animals for blood, even crocodiles
  • they can be a major nuisance to humans enjoying the beaches and creek walks particularly in late Summer/early Autumn in Victoria as their bite is painful and they often leave wheals as they bite by slashing through skin with their serrated scimitars to cause bleeding
  • they tend not to have survived in areas of human occupation as humans do not get along well with them and presumably have pushed them into less occupied areas over the years.

life cycle

  • eggs are laid on grass blades or foliage overhanging wet sites
  • on hatching, the larvae fall into the water, moist earth, mud or sand and are voracious predators of earthworms, snails and other insects
  • after 3-4 months in the larva phase, they move into relatively dry soil for pupation, burying themselves 5 to 15 cm below the soil surface
  • the pupation phase lasts about 12 days
  • adult fly emerge 2-6 months after pupation, usually after a period of rain in the Summer months (longer period of activity in northern parts of Australia compared to southern Australia)

adult fly behaviour

  • adults typically fly near water bodies and / or near cattle during the daylight hours
  • adults only live 3-4 weeks
  • males only feed on nectar and pollen and cannot bite
  • the females are the only ones which bite as they need protein for reproduction, and after mating, they disperse, travelling many kilometres in search of blood meals.
  • they are particularly influenced by the weather and behaviour will respond to changes in barometric pressure, wind, cloud cover and temperature
  • they are most active in Summer in open sunny areas with only slight breezes
  • they tend to target warm, dark objects which it thinks is a warm-blooded animal (including dark backpacks and clothes)
  • other stimuli include carbon dioxide and odours (presumably from perspiration)
  • they then circle looking for open space on skin above or below the dark region (usually your legs or your back if you are not wearing a shirt)
  • fly traps utilise this behaviour to attract the fly then decieve them to fall into soapy water in which they drown


  • most people only develop wheals and urticaria but some develop fever and general disability, and some develop cellulitis
  • Australian species are not known to spread disease although one species can spread filaria (nematode) between wallabies and kangaroos

avoiding bites

  • your best protection is:
    • avoid locations where the flies are prevalent (ie. near water)
    • use of lotion type repellents that contain 5-20% DEET
    • wear long sleeved shirts and long trousers
    • kill them by hitting them with a water bottle or your hand when they land on your legs
    • avoid open sunlit areas (pastures and beaches) and resort to shaded areas or forests
    • use light colored clothes and backpacks
  • they seem to attack most in sunlit areas - presumably attracted to perspiration as they often will land on your backpack

other biting flies in Australia

  • the stable flies (Family Muscidae)
    • the stable fly, Stomoxys calcitrans is a vicious biter with piercing and sucking mouthparts that can easily penetrate socks and stockings to feed on blood
    • they look similar to the common house fly and are about 8mm long, are grey with 4 dark stripes on the thorax
    • mainly found on rural farms, particularly near horse stables and compost
    • may breed in sea-weed on beaches
  • the black flies (Family Simuliidae)
  • the biting midges or sand flies (Family Ceratopogonidae) - these are a particular problem on beaches, particularly to the north
  • mosquitoes (Family Culicidae)
australia/march_flies.txt · Last modified: 2021/04/01 22:02 by gary1

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