Blowfly strike hitting flocks earlier, farmers say

A SURVEY by Elanco Animal Health has found that 70% of UK sheep farmers have

seen cases of blowfly strike prior to shearing, highlighting the need to consider earlier

application of preventative treatments.

The study, designed to understand the parasite pressures facing sheep farmers amid

changing weather patterns, suggests blowfly activity is beginning earlier than it was five

years ago.

Carolyn Hogan, ruminant technical consultant at Elanco, says Met Office data shows a

general trend towards increasingly milder weather, with temperatures this March being

above average.

"Our aim was to understand how this shift in weather might be influencing when farmers are seeing parasites on farm," she said.

"The results corroborate the fact that blowfly emergence is happening earlier than it has in

the past, with reports of strike as early as March and April in some regions."

Ms Hogan says the pre-shear period is high risk for sheep with full fleeces, particularly when

the weather is mild and wet.

This was reflected in the survey where results showed a large proportion of farmers across

the UK have seen cases of strike in ewes before shearing.

Ms Hogan said: "Blowfly emergence is driven by temperature. Once the temperature rises above 9C, flies begin to accumulate what we call degree days.

"Warmer conditions accelerate the accumulation of these degree-days, meaning that with

higher temperatures earlier in the season, we’re seeing blowfly emergence sooner than in

previous years."

Carolyn Hogan

To help mitigate the risk of struck sheep, Ms Hogan recommends an early application of an

Insect Growth Regulator (IGR).

"Blowfly strike can be costly for farmers and just one struck sheep is one too many, so

applying a preventative treatment before blowflies become a problem can help reduce this

risk and also limit the number of flies reproducing throughout the season,” she said.

"If you’ve got ewes and lambs in for treatments post-lambing then it’s worth considering an

IGR application for your ewes at the same time, to provide cover from blowfly strike during

the pre-shearing period when they are particularly vulnerable.

"CLiKZiN is an ideal choice as it offers eight weeks’ protection - often enough to cover ewes

ahead of shearing - after which a longer-duration product such as CLiK Extra can be used

after shearing to protect sheep through the main summer period.

"CLiKZiN has a meat withdrawal of just 7-days, making it a suitable option for

fat lambs too."

Ms Hogan says while treatment timing and product choice are important, correct application

will ensure you get the most out of preventative treatments.

"When using products from the CLiK range, following the four-stroke application method will help you to get optimal results," she said.

"Also, calibrating your dosing gun ensures that the right amount of product is applied,

reducing waste and allowing you to get the most from each application."

For more information on early preventative blowfly strike treatment, speak to your local SQP.