Blowfly warning as warm temperatures remain

Sheep farmers are being warned to treat for blowfly strike as prolonged hot weather increases the number of animals at risk.

Experts are advising farmers to be extra vigilant in looking for signs of blowfly strike. They also encourage farmers to use preventative treatments in order to provide full fleece protection against this potentially deadly disease.

Blowfly strike happens very quickly. After hatching, the blowfly maggots feed at the skin surface, taking two to three days to fully mature. They then drop off and complete their lifecycle in the soil. The foul-smelling wound created by feeding maggots is a powerful attractant for more egg-laying female blowflies. Infestations can therefore build up quickly especially in the hot weather.

Richard Wall, professor of zoology at Bristol University explains: “Once adult flies are on the wing, blowfly strike happens extremely quickly. If an infestation is missed the reality is that a sheep can die from repeated strikes within one to two weeks.

“Recent research shows that a 3C increase in average seasonal temperature would be expected to approximately double the frequency of strike in lambs and lead to four times more strike in ewes.”

Beating blowfly strike

  • The recent hot weather is increasing the number of animals at risk of blowfly strike – a 3C increase in average seasonal temperature approximately doubles the frequency of strike in lambs.
  • Blowfly strike happens very quickly and infestations can build up quickly especially in the hot weather.
  • Blowfly strike can be easily prevented through the use of products which contain insect growth regulators.

Therefore, it is important that farmers are aware of the different treatment options available for blowfly and how they work. Incorrect product choice may result in outbreaks of strike and eventual death of a struck animal.

Fiona Anderson, vet at Novartis Animal Health comments: “Some farmers who have treated with a shorter acting blowfly product which doesn’t offer full fleece protection have been caught out with blowfly strike due to the recent hot weather.

“As this weather looks set to continue, blowfly protection will be required for some time to come.”
Fiona Anderson, Novartis Animal Health

“As this weather looks set to continue, blowfly protection will be required for some time to come. Therefore, an insect growth regulator (IGR), which provides long-lasting, full-fleece protection may be the better choice.

“If animals have been struck, farmers need to first treat them with a product that kills maggots. They should then treat the rest of their flock, both ewes and lambs, with an IGR. IGRs prevent the development of the damaging second- and third-stage maggots which are responsible for causing fly strike and stock damage.”

A new report Protecting the Future of Your Flock: Blowfly Strike in the Spotlight commissioned by Novartis Animal Health found that 59% of sheep farmers have reported a case of strike as late as October, and almost a third (30%) as late as November, suggesting that if farmers do not act now and use a preventative product, their flock may be at risk of blowflies for several months to come.

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