Welfare emergency: Flystrike (cutaneous myiasis) causes intense pain and, if untreated, rapid death. It is a welfare emergency — affected animals require immediate treatment. Prevention is far preferable to management of established strikes.
What Is Flystrike?
Flystrike occurs when blowflies (primarily Lucilia sericata in the UK) lay eggs in moist, soiled wool or in wounds. Larvae (maggots) hatch rapidly and begin feeding on the sheep's flesh. The condition is acutely painful, spreads rapidly, and is fatal if untreated. In the UK, flystrike season typically runs from April to October, peaking in warm, humid conditions.
Risk Factors
Dag (faecal soiling around the tail and back legs) — most common predisposing factor
Body strike: in warm conditions blowflies may strike the back and shoulders of undamaged animals
Prevention Strategies
Dagginess control: Treat scouring promptly; crutching (removing soiled wool from dock region) before high-risk periods
Timely shearing: Removes long fleece before peak season; reduces fly strike risk by eliminating the warm moist microenvironment flies require
Preventive insecticide treatment: Organophosphate or pyrethroid-based pour-on or dip treatments provide season-long protection. Veterinary advice essential for product choice and frequency given emerging resistance.
Flystrike vaccines: Research programmes underway; not yet commercially available in the UK
Genetic selection: Breeds with reduced dagginess, better wool structure, and natural resistance traits are being developed
Detection & Treatment
Early detection is critical. Check sheep at least daily during risk periods, and more frequently in warm weather. Signs: restlessness, kicking at flanks, biting at affected area, separation from flock, distinctive smell. Treatment: remove all maggots and affected wool, clean wound thoroughly, apply licensed insecticide to wound area and surrounding fleece. Severely affected animals require veterinary attention; analgesia should be provided. Badly struck animals may need to be euthanised on welfare grounds.