Flystrike – strike now before they do - Elders Rural Services
Elders sheep farm

Flystrike – strike now before they do

Flystrike in Australian sheep is a serious issue, causing significant suffering and pain to the animal and estimated to cost the industry $280 million annually.1

The cost comes not just from loss of production (ie: poor quality wool), but also the cost of chemicals and time spent attending the inflicted animal. As the recent abundant rains across Australia give way to the heat and often humidity of an Australian summer, now is the time to strike to reduce the risk.

What is flystrike?

Flystrike is the work of the Australian sheep blowfly (Lucilia cuprina). The female blowfly is attracted to sheep with damp wool, particularly wool stained and wet from urine and faeces. She lays her eggs in the fleece of the sheep.

After hatching the larvae (maggots), feed on the flesh of the sheep, and cause chemical damage due to the ammonia they excrete. Eventually they leave the sheep to pupate in the soil.

Prevention is better than cure.

While sheep with a high wrinkle level and poor worm control are more susceptible to flystrike, there are many ways to reduce the risk of flystrike, both chemical and non-chemical.


  • Crutching and drenching (to prevent dags) or shearing where possible.
  • Regular inspection, particularly after periods of rain.
  • Moving sheep from area if infestation is found. The flies are territorial and seldom travel more than three kilometres from where they hatch, so move the sheep out of the three km radius.
  • If found, treat early and stop the first wave. This will avoid a potentially disastrous second and any subsequent waves.

Chemical options

Chemicals vary in protection length and withholding periods, so consult your Elders livestock advisor for the best option for your situation. Some of the popular options include:

  • Clik and Vetrazin. Active ingredients: Dicyclanil and cyromazine. Resistance to these chemicals has been reported in some areas, see note* below.
  • Extinosad. Active ingredient: Spinosyn. No known resistance and zero days wool and meat withhold.
  • Iverlab Blowfly and Lice. Active ingredient: Macrocyclic lactones. No known resistance and short meat and medium wool withhold.
  • Avenge Fly and Lice. Active ingredient: Neonicotinoids. No known resistance.

As with all chemical use, refer to the label and use strictly as directed.

*Note: resistance to the chemicals cyromazine and dicyclanil is localised and depends on several factors, including:

  • history – how often and for how long have they been used
  • under-dosing – sub-lethal applications encourage resistance
  • timing of treatment – reactive rather than proactive treatment allows fly numbers to build, increasing the chance of resistance developing.

In other words, these chemicals may well be effective on your property, despite what you hear at the pub!

Don’t even consider using diazinon – it is carcinogenic and pretty much impotent.


While environmental factors may be combining to produce ideal conditions for flystrike this summer, preventative action now can save a lot of stress and suffering for both you and your herd.

Elders offers a range of animal health products to keep your flock in prime condition all year round.

View the range
  1. WA Department Primary Industries and Regional Development.

The information contained in this article is given for the purpose of providing general information only, and while Elders has exercised reasonable care, skill and diligence in its preparation, many factors (including environmental and seasonal) can impact its accuracy and currency. Accordingly, the information should not be relied upon under any circumstances and Elders assumes no liability for any loss consequently suffered. If you would like to speak to someone for tailored advice relating to any of the matters referred to in this article, please contact Elders.