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Blowfly Strike Prevention

Reducing Blowfly Fly Strike

Caroline Dawson, BVSc, MRCVS, Elanco

Blowfly strike is a welfare issue and carries significant economic costs. It has been shown that every year, 80% of flocks will have one or more cases of fly strike.

According to Caroline Dawson of Elanco “No matter how good a product is, if it is not applied correctly, it is unlikely to work to its full potential”


You can check the latest blowfly strikes in your local area with the handy Elanco Fly Tracker by clicking the banner below:

Guide to avoiding blowfly strike

1. Use preventative products early in the season: Using targeted blowfly treatments of narrow spectrum products is recommended. Pour-ons containing the Insect Growth Regulator (IGRs) dicyclanil, such as Clik and Clikzin can be used to stop the development of the first stage larvae into the second and third stage larvae. As these are the stages causing damage, if used correctly, an IGR will prevent fly strike. However, these products will not treat existing strike (second and third stage maggots). Also by treating early, the number of blowflies will be reduced which, in turn, will reduce the number for the remainder of the season.


2. Apply the product correctly: Correct application is vital and includes simple things from checking guns are delivering the correct amount of product, to ensuring the instructions on the pack are followed. Particular areas to focus on include:

• Correct equipment

• Correct dose

• Product administered in the correct way/place

e.g. ensuring the product is placed down the midline is crucial for many products


3. Strategic culling: Evidence shows that hereditary factors may exist and the culling of breeding ewes and rams that are continually struck could be considered. Culling should also be considered for ewes with deformed genital openings and narrow breeches that result in soiling.


4. Shearing and dagging: Complete shearing can temporarily reduce the risk of strike, but this risk rapidly increases as the fleece grows. Ewes can become flyblown even after  shearing. Routine crutching and dagging will reduce the risk of strike if started at the beginning of the risk period and repeated every four to six weeks.


5. Ensuring adequate worming protocols: Having a good worming strategy in place is important not only for the management of nematodes, but also for the management of fly strike. Decreasing the amount of scouring will lower the amount of soiled fleece and make the sheep less attractive for flies.


6. Reduce the incidence of footrot by using the right footcare products


7. Decreasing the number of flies on the farm: Good on farm management strategies can decrease the challenge and the incidence of blowfly strike e.g. through the use of environmental insect control products, such as Neporex® to reduce the fly hatch from middens and dung heaps.

Don’t get caught out by flies this summer, speak to your vet or Mole Valley SQPs today to get a fly control strategy in place for your flock.

Source Details

 625 Mole Valley Farmers Newsletter

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