Sheep Fly Strike: Prevention as the Primary Welfare Strategy

Blowfly strike is one of the most severe welfare conditions in sheep farming, causing excruciating tissue damage that is highly preventable.

Key Facts

Blowfly strike (myiasis) occurs when flies lay eggs in moist, soiled wool, and larvae burrow into living tissue
Australian merino sheep lose over AUD $280 million annually to flystrike-related losses
A struck sheep can suffer extensive skin and muscle destruction within 24-48 hours of infestation
The primary prevention is crutching (removing wool from the breech area), mulesing, or chemical prophylaxis
Mulesing — surgical removal of breech skin folds — is highly controversial for its own welfare costs
Non-mulesing alternatives including selective breeding for bare-breech genetics are showing promise

Welfare Considerations

Fly strike causes extreme suffering. Larvae produce enzymes that liquefy tissue, creating deep wounds while the animal remains fully conscious. Affected sheep show signs of severe pain: stamping, biting at the affected area, and collapse in advanced cases. Because symptoms can be subtle early on, daily monitoring during fly season is critical. The welfare trade-off around mulesing — causing acute pain to prevent a potentially more severe condition — is genuinely complex. Selective breeding programs producing plain-bodied, bare-breech sheep offer the most ethically coherent long-term solution, eliminating both fly strike risk and the need for mulesing.

What You Can Do

Support wool producers using mulesing-free and fly-strike-resistant breeding programs
Choose wool products certified mulesing-free where possible, and encourage retailers to source accordingly
Advocate for investment in selective breeding research to develop inherently flystrike-resistant sheep breeds
Support welfare standards requiring daily flock monitoring during blowfly season in wool-producing regions