Parasitic Maggots in Sheep

Flystrike in Sheep

• Myiasis condition caused by parasitic flies infecting domestic sheep.
• Thick wool contaminated with urine and fecal matter creates breeding grounds for maggots, even without wounds.
• Flies lay eggs on soiled wool or open wounds; maggots hatch and burrow into the sheep's flesh.
• After larvae develop, flies lay eggs on new or infected sheep, perpetuating the cycle of infestation.
• Symptoms include agitation, loss of appetite, unpleasant odor, and matted wool, attracting more flies.
• Ammonia poisoning can result from flystrike, making it potentially lethal for sheep.
• Infestation causes economic losses due to stock degradation and increased management expenses.

Flystrike Causes and Effects

• In Australia, Lucilia cuprina accounts for approximately 90% of infestations.
• Chrysomya rufifacies is the main secondary pest, targeting wounds from L. cuprina.
• Flystruck sheep show green or wet-looking fleece patches, particularly around the haunches, tail, or wounds.
• Penile area in male sheep is also a common flystrike site.
• Infected sheep display agitation behaviors such as foot stamping or nibbling at their body.
• Severe cases can lead to shedding of wet-looking wool and produce a strong characteristic odor.

Environmental Factors

• Optimal conditions for flystrike include temperatures between 15–38°C (59–100°F), recent rainfall, and wind speeds under 9 km/h (5.6 mph).
• UK peak breeding season for green bottle flies generally occurs in late June or July, though infestations can happen any time warm, damp conditions are present.

Prevention and Management

• Various preventative measures exist to minimize flystrike risk in sheep flocks.
• No single measure can entirely prevent flystrike; regular treatment and monitoring are essential for effective management.