Livestock Fly Strike and Parasite Welfare

Fly strike (myiasis) causes extreme suffering in sheep and other livestock. Prevention and prompt treatment are essential welfare obligations for livestock keepers.

Key Facts

Blowfly strike (myiasis) occurs when blowflies lay eggs in moist, soiled wool or skin; maggots hatch within hours and begin destroying living tissue.
Affected sheep show restlessness, biting at affected areas, and eventually collapse; if untreated, fly strike is fatal within days.
Warm, wet weather significantly increases fly strike risk — climate change is extending the risk season in many regions.
Prevention includes daggings (removing soiled wool), insecticide treatments, and genetic selection for flystrike-resistant breeds.
Merino and other fine-woolled breeds are more susceptible due to skin folding and dense fleece.
Mulesing — surgical removal of breech skin — is a controversial prevention method raising its own welfare concerns.

Welfare Considerations

Fly strike represents one of the most acutely painful conditions in farmed livestock. Maggots consume living flesh while the animal remains conscious, causing tissue destruction, toxaemia, and intense pain. The speed of progression — from first eggs to life-threatening infestation in 24-48 hours — means that livestock keepers must inspect animals daily during risk periods. Failure to do so is a welfare failure with serious legal consequences in many jurisdictions. The controversy around mulesing highlights the complexity: a painful surgical procedure that prevents a potentially more painful condition. Alternatives — including selective breeding, pain-relieved mulesing, and non-surgical prevention — are actively being developed and should be prioritised.

What You Can Do

If you keep sheep, implement a daily inspection programme during warm weather and act immediately on any signs of strike.
Use preventive treatments (appropriate insecticides, crutching) and work with your vet to create a fly strike prevention plan.
Support breeding programmes developing fly strike resistant sheep varieties.
Choose wool products from farms committed to fly strike prevention without surgical interventions.