WINTER BONUS MAGAZINE 2025

Blowfly strike is a serious and potentially fatal condition affecting sheep worldwide. It occurs when blowflies lay their eggs on the sheep’s skin, and the hatched larvae (maggots) feed on the animal’s tissue. This condition not only causes immense suffering to the affected animal, but also leads to significant economic losses for farmers due to reduced productivity, treatment costs, and potential mortality. Understanding the causes, risk factors, and management strategies for blowfly strike is essential for effective prevention and control. What causes blowfly strike? Blowfly strike is primarily caused by the green bottle fly (Lucilia sericata), though other species of blowflies can also be involved. Female blowflies are attracted to sheep by the smell of moisture, wounds, or soiled fleece, particularly around the hindquarters. They lay their eggs in warm, damp areas of the sheep’s body, such as: Soiled fleece (due to diarrhoea or urine stain- ing) Wounds or skin abrasions Damp or dirty wool caused by prolonged wet weather Areas affected by foot rot or other infections Once the eggs hatch, the larvae burrow into the sheep’s skin and begin feeding on the tissue, causing severe pain, tissue damage, and secondary infections. If left untreated, the condition can lead to toxaemia, septicaemia, and death. Risk factors for blowfly strike Several factors increase the risk of blowfly strike in sheep: 1. Weather conditions: Warm, humid weather accelerates the life cycle of blowflies, increasing the likelihood of infestation. Prolonged wet conditions also keep the sheep’s fleece damp, making them more attractive to flies. 2. Poor hygiene: Sheep with soiled fleece, particularly around the tail and hindquarters, are at higher risk. Diarrhoea or urinary incontinence can exacerbate this issue. 3. Wounds or skin damage: Any open wounds, cuts, or skin infections provide an ideal environment for blowflies to lay their eggs. 4. Wool type: Sheep with dense or wrinkled fleece are more susceptible, as these traits trap moisture and make it harder to detect early signs of strike. 5. Overcrowding: High stocking densities can increase the risk of faecal contamination and the spread of infections. Blowfly strike in sheep: p: understanding, prevention, and treatment Winter 2025 BONUS www.agribonus.co.za 2