Flystrike Prevention in Sheep: Protecting Animals During Warm Months

Blowfly strike is one of the most welfare-significant conditions in sheep, causing rapid, severe suffering as fly larvae consume living tissue, but is highly preventable with systematic management.

Key Facts

Blowfly strike (myiasis) occurs when flies lay eggs in damp or soiled wool, and larvae hatch and begin eating living flesh
The primary blowfly responsible in the UK and Australia is Lucilia cuprina (sheep blowfly)
Affected sheep can go from normal to severely compromised within 24-72 hours if not detected
Risk factors include wet conditions, dags (faecal soiling), wounds, foot rot, and fleeces in poor condition
Prevention strategies include chemical prevention (organophosphates, insect growth regulators), fly trapping, and regular inspection
Mulesing of Merino sheep in Australia surgically removes breech wool-growing skin to reduce strike risk but has significant welfare implications

Welfare Considerations

Blowfly strike represents acute, severe suffering: as larvae consume living tissue, affected sheep experience intense pain, the smell of the wound attracts more flies, and without intervention the animal dies from septic shock, toxemia, or blood loss. Yet the condition develops under the wool where it is invisible until advanced, making early detection dependent on behavioral observation (separation from flock, reduced grazing, restlessness) or systematic physical inspection. Producers who inspect sheep regularly and catch strike early can treat effectively; those who inspect infrequently allow suffering to progress to severe stages. The mulesing debate highlights the difficulty of welfare tradeoffs: mulesing causes acute surgical pain but significantly reduces lifetime flystrike risk for individual sheep. Alternatives including selective breeding for bare-breech phenotypes, pain-managed mulesing, and non-mulesing programs combined with excellent management offer paths forward.

What You Can Do

Inspect sheep at least twice weekly during high-risk warm, wet weather periods
Check specifically around the breech, wounds, and feet - areas most vulnerable to strike
Apply preventive chemical treatments at appropriate intervals, following resistance management guidelines
Clip dag-prone areas (around the tail and breech) to reduce soiling and fly attraction
Learn to recognize early behavioral signs of struck sheep: separation, reduced grazing, head down, tail-wagging
Support research into flystrike-resistant sheep genetics as a long-term welfare solution