Red blowfly warning issued for South of England and East Anglia
30th April 2025
Sheep farmers in the South of England and East Anglia have been warned of the risk of blowfly strike as the local Blowfly Watch risk alert has been raised to red.
The free Blowfly Watch service, run in partnership with NADIS, uses a combination of factors – including soil temperature and humidity – to predict a blowfly strike risk in a 40km area.
Matt Colston, ruminant technical consultant at Elanco, said that it is worth considering early preventative action when the service issues risk alerts in your area.
“Damage happens fast – it can take as little as 36 hours from an egg being laid on a sheep to maggots eating its flesh – so prevention is better than waiting to see a struck lamb before treating the whole flock.
“You can protect your flock by applying an Insect Growth Regulator (IGR), such as those in the CLiK range,” he added.
READ MORE: Blowfly warning issued for South West sheep farmers
Expert’s top tips
The expert explained that the range provides options for all types of sheep, whatever the management system, with protection periods ranging from eight to 19 weeks, and meat withdrawal periods ranging from seven to 40 days.
Mr Colston’s top tips for applying a preventative treatment include:
- Use an appropriate applicator gun with a fan spray nozzle and be sure to carefully calibrate it before use.
- Apply to a clean fleece; clip or dag any dirty animals before application.
- Apply the product in a band approximately 10 cm wide (holding the gun approximately 45cm from the sheep).
- Apply the total required dose one quarter at a time, using the four-stroke method – from mid-shoulder to the middle of the back, from the middle of the back to the top of the tail, from one side of the tail to the crutch, and from the other side of the tail to the crutch.
Mr Colston said that the efficacy of preventative treatment relies on the product being applied to clean sheep – aided by effective worm control, as well as actions such as dagging and timely shearing.
“Worm management plays a valuable role in preventing strike, because scouring due to worms, can cause dirty backends and encourage flies.
“Regularly faecal egg counting will help identify worm burdens early and prompt treatment before lambs scour,” he concluded.
Farmers can sign up for Elanco’s Blowfly Watch alerts online here at and report cases of strike on the Elanco Blowfly Tracker.
READ MORE: Free tool relaunches to help farmers manage risks of blowfly strike
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