Blowfly – Don’t be fooled by cold weather

SHEEP farmers are being urged to treat against blowfly and midges as normal this spring – despite one of the coldest winters for 30 years.

“Producers mustn’t think that the freezing weather after Christmas has killed off all the fly larvae and they don’t have to treat their animals this year,” said a spokesman for the Sheep Veterinary Society.

“They cannot afford to be complacent and they must ensure that they protect their sheep as usual this year, because blowflies could still cause problems this spring.”

Blowfly strike is believed to have affected some 750,000 sheep on 80% of UK farms last year. Worryingly for the lamb crop, there is a much higher risk of lambs being struck after ewes have been sheared.

“Early treatment this summer will protect your lamb crop from the risk of blowfly strike, improve overall productivity and be more cost effective,” said Simon Harris, veterinary advisor for Novartis Animal Health.

Long-term prevention was the best strategy due to the varying onset of the fly season. Insect growth regulators stopped fly larvae fromed developing and offered the longest period of protection.

Preventative treatment, typically in late spring, would help farmers avoid the impact of high fly challenge on lamb growth rates and ewe fertility, which results from reduced food intake, Mr Harris explained.

“Also, by treating smaller lambs, there is less chance that withdrawal times will impact on lamb marketing,” he added.