Blowfly Strike in Sheep: Prevention and Emergency Welfare Management

Blowfly strike causes one of the most severe welfare emergencies in UK sheep farming — prevention through shearing, cleanliness, and insecticides is essential.

Key Facts

• Blowfly strike kills thousands of UK sheep annually and affects up to 80% of farms
• Lucilia sericata (green bottle fly) is the primary blowfly species causing strike in UK sheep
• Maggots consume living tissue causing severe pain, toxin absorption, and rapid deterioration
• Untreated strike can kill a sheep within days through toxemia from maggot products
• Prevention using insecticidal treatments (organophosphates or IGR products) provides 8-16 weeks protection

Welfare Considerations

Blowfly strike causes horrific welfare suffering — maggots feeding on living skin and muscle tissue while the sheep is still alive create wounds that expand rapidly, releasing toxins that cause depression, collapse, and death. Affected sheep show characteristic behavior: stamp their feet, bite at themselves, break away from the flock, and show progressive deterioration. The welfare emergency requires immediate action: clipping the wool from around and beyond the struck area, physical removal of all maggots (an unpleasant but welfare-critical task), topical treatment with an approved wound spray, systemic treatment for toxemia, and veterinary assessment of severe cases. Prevention through timely shearing, dagging, and application of long-acting insecticide treatments during fly season is the only welfare-effective strategy.

What You Can Do

• Apply long-acting blowfly prevention treatment (organophosphate or IGR) before the fly season begins
• Shear sheep before fly season and dag any dirty sheep promptly throughout summer
• Walk the flock daily during high-risk periods (May-September) to detect struck sheep early
• Treat struck sheep immediately: clip, remove maggots, treat wound, and monitor for toxemia
• Record all strike cases to identify prevention program gaps and persistently affected individuals