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  • Writer's pictureFlockFinder Team

FlockFinder Guide to Fly Strike 🪰


Avoid Flystrike this summer


Protect your sheep from blowfly strike!

Blowfly strike is a serious concern for sheep farmers, affecting up to 80% of flocks in the UK every year.


This parasitic condition, caused by the greenbottle fly, can lead to reduced performance, secondary infections, and even death.

But fear not! There are preventative measures you can take to keep your woolly friends safe.

  1. Start early: Apply a preventative treatment (e.g. IGRs) at the beginning of the blowfly season. Choose the right product based on your sheep's age, shearing, and lambing dates. Multiple applications may be necessary.

  2. Keep it clean: Minimize soiling of their hindquarters by practicing regular dagging, crutching, and shearing. A good worm control strategy is also vital. Tail docking can help reduce the risk in lowland flocks.

  3. Promptly treat lameness: Flies are attracted to footrot wounds, so address lameness issues promptly. Attention to foot health is crucial to avoid foot strikes.

  4. Reduce the fly population: Inexpensive fly traps have been shown to decrease strike incidence by up to 80%!

  5. Consider grazing strategies: During high-risk periods, choose more exposed pastures that are less favorable to flies.


Remember, prevention is better than cure! By applying an appropriate product before the risk period, you can protect your sheep from blowfly strike.


Blowfly products 💊

There are three types of topical products recommended for blowfly control in sheep farming: insect growth regulators (IGRs), cypermethrins, and deltamethrin.

  • Insect Growth Regulators (IGRs) - prevent blowfly larvae from developing and stop the lifecycle, providing protection against strike for 8 to 16 weeks. (They do not treat existing strikes.)

  • Cypermethrins - can treat existing strikes and offer protection against future strikes for 6 to 10 weeks.

  • Deltamethrin - products only treat existing strikes.

Scops has a handy guide to treatment options here.


Plunge dipping in an organophosphate (OP) solution can also treat and prevent blowfly strikes, but it is recommended to use topical products specifically targeting blowflies whenever possible, rather than relying on OPs unless necessary. This recommendation aims to reduce environmental impact and the development of resistance in parasites.


Read product instructions carefully, use the right equipment, and always consult your vet or advisor if you have any questions.


FlockFinder Treatment Summary

Record your treatments in FlockFinder 📱


Many blowfly treatments have long withdrawal periods (some up to 49 days!), so it's even more important to keep your medicine book up-to-date.


FlockFinder lets you record treatments while out in-the-field! Individual and bulk treatments can be recorded with just a few taps, with dosages and withdrawal periods automatically calculated to help keep your records accurate and up-to-date.


Find out more about FlockFinder here.

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