Blowfly strike risk is becoming increasingly unpredictable due to changing weather patterns requiring enhanced vigilance with cases now seen as early as March and as late as December.

Fly strike not only affects the welfare of the animal but also the bottom line of a business with estimations of £10 in production loss per lamb, according to a report by Bimeda, the makers of Ectofly, soon adding up when more than 75% of farms are affected per year.

Elanco Animal Health’s ruminant technical consultant, Matt Colston, also said changing weather patterns meant the fly season was starting earlier and lasting longer.

“This means farmers should be prepared to apply protection early on in the season, as preventative treatment is always the most cost-effective strategy against blowfly strike.”

He says the active season for the main species causing blowfly strike in the UK – green bottle – has lengthened, with the Blowfly Forecast being a really useful tool for monitoring activity, which tends to start as soon as soil temperatures rise above 9°C.

Elanco’s Blowfly Forecast, which is available online at https://www.farmanimalhealth.co.uk/sheep/sheep-blowflies/blowfly-risk-forecast, can be used to assess risk alongside considering other factors.

Prevention:

Due to the multitude of factors which can predispose to fly strike, fly prevention products are only part of the solution, with other activities being critical to reduce risk:

Annual shearing and regular dagging/crutching of soiled fleeces. Shearing results in a 95% reduction in the incidence of strike.

Docking – where appropriate, and when done in conjunction with the law. Docked lambs are five times less likely to suffer from fly strike.

Check animals frequently during high-risk period.

Remove any carcases promptly.

Reduce scouring (gastrointestinal parasite management, good nutrition).

Any wounds should be monitored closely until resolved.

Reduce the incidence of footrot.