Livestock Cropping & Pasture General Farm

Managing Fly Strike

What is fly strike?

Fly strike occurs when blowflies lay eggs on the skin of the sheep. The eggs hatch into larvae (maggots), which feed on the tissue of the live sheep. Flystrike produces severe inflammation, systemic toxaemia, and eventually death.

What are predisposing causes of fly strike?

  • Most fly strike is caused by the Australian Sheep Blowfly, a green bodied insect.  The vector must be present.
  • Correct temperature range, 15-36oC.
  • Moist conditions
  • Sites attractive to the fly; e.g. moist, urine, faeces, wrinkles, foot rot contamination on sheep’s sides.

Is fly strike a significant production issue?

Fly strike is estimated to cost the Australian sheep industry about $280 million per year.  It is a major welfare issue as it causes great suffering to affected sheep. It is estimated that up to 3 million sheep die in Australia from fly strike each year.

How can fly strike be managed?:

Short term management practices include:

  • Chemical control by spraying or dipping
  • Crutching
  • Strategic shearing.
  •  Control of worms
  • Keeping the sheep clear of ‘dags’ – mattered wool containing faeces
  • Strategically siting fly traps near sheep camping areas.

Long term strategies comprise breeding for reduced dagginess or wrinkles.  However, this option only works if it is applied in ram breeding flocks.