Sheep farmers warned as blowfly risk rises to red

Sheep farmers across the UK are being urged to take action after Blowfly Watch raised its national risk alert to red, signalling a high threat of blowfly strike due to recent weather conditions.

The Blowfly Watch risk forecast, developed with the National Animal Disease Information Service (Nadis) draws on Met Office data, including soil temperature and humidity, to assess strike risk in 40sq km zones across the country.

The service is designed to help farmers anticipate blowfly activity and protect their flocks from one of the most serious seasonal threats to sheep health.

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The recent spike in temperatures has accelerated the development of the blowfly population, driving the risk to red in certain areas, particularly in the north of England, the west of Scotland, and Northern Ireland.

“Blowfly strike can occur rapidly – in as little as 36 hours after eggs are laid,” Nadis warns, highlighting the need for timely preventative action.

The disease is thought to affect more than 80% of sheep farms in the UK.

“Blow” refers to the laying of eggs by flies, and “strike” is the damage caused by the maggots.

In the UK, strike is caused primarily by the green bottle fly, Lucilia, which seeks decomposing matter to lay her eggs.

Carcasses, dirty backends, foot rot lesions, and open wounds are all good egg-laying sites. 

While very dry conditions can prevent eggs from hatching and maggots from developing, even a short period of rainfall could lead to a sharp rise in cases.

Shearing and dry weather may offer some protection, but experts caution that on-farm conditions can vary, and individual risk levels may be higher or lower than forecasted.

Early signs of strike:

• Irritation
• Nibbling at tail head
• Increased swishing of tails
• Rubbing
• Further signs of discomfort in lame animals

Farmers can sign up for free Blowfly Watch alerts to monitor conditions.