Sheep Fly Strike Prevention: Managing Flystrike Welfare Humanely

Blowfly strike is one of the most severe welfare problems in sheep farming, causing rapid, extreme suffering. Prevention and early detection are critical welfare priorities.

Key Facts

Blowfly strike (myiasis) occurs when blowflies lay eggs in moist wool, with larvae hatching and burrowing into sheep flesh within hours
Affected sheep experience intense pain from tissue destruction — heavily struck sheep can be killed within days
The UK alone loses an estimated 80,000 sheep annually to flystrike, with many more suffering sublethal strikes
Wool breeds (Merino, Corriedale) are most susceptible; shorn sheep and those with healthy skin are less vulnerable
Insecticide treatment (organophosphates, synthetic pyrethroids, cyromazine) applied prophylactically can protect sheep for up to 16 weeks
Mulesing — surgically removing wool-bearing skin from the breach — is a controversial strike prevention practice banned in New Zealand and voluntarily phased out by some producers

Welfare Considerations

Blowfly strike causes some of the most severe acute suffering experienced by farm animals anywhere in the world. The progression from eggs to tissue-destroying larvae is rapid, and affected sheep show extreme pain responses — teeth grinding, kicking at affected areas, and progressive deterioration that can lead to death within days of heavy infestation. Prevention is categorically more welfare-positive than treatment: regular monitoring during high-risk periods (warm, humid weather), strategic insecticide application, and breeding or selection for susceptibility-reducing traits (reduced skin wrinkling, better fleece shedding) all reduce strike incidence. For strikes that occur despite prevention, early detection and immediate treatment — removing wool from the affected area, cleaning the wound, applying treatment — limits suffering duration. Mulesing as a prevention method is itself painful without analgesia; the welfare debate centers on whether the chronic strike prevention benefit outweighs the acute surgical pain.

What You Can Do

Support lamb and mutton producers who use regular monitoring and preventive insecticide treatment during high-risk periods
Advocate for mandatory mulesing analgesia requirements in countries where mulesing is practiced
Support research into non-mulesing flystrike prevention including selective breeding and biological control
Choose wool products certified under standards that prohibit mulesing or require analgesia when practiced
Learn about flystrike to understand why it is treated as one of the most urgent welfare priorities in sheep farming