August 25

Early Season Fly Treatment


Act now to reap benefits throughout the fly season!

It seems odd to be discussing blowfly prevention while the days are short and temperatures cold. However, the seasonal nature of fly activity provides a unique opportunity to plan ahead.

Strategically treating sheep early in the season with an effective and long-lasting chemical prevents fly numbers from building up by removing the host environment required for flies to reproduce.  This can significantly reduce subsequent fly pressure and the risk of flystrike in the season ahead.

The Australian sheep blowfly Lucilia cuprina is the primary fly species responsible for flystrike. This species of blowfly is largely dependent on sheep as a breeding resource.1

Fly numbers can build up very rapidly under suitable environmental conditions, assuming susceptible sheep are available.

In cooler conditions at the end of the fly season, development is inhibited or “arrested” at the prepupae stage and development is not resumed until conditions are again suitable. The increase in soil temperature in spring in south-eastern Australia has been shown to trigger synchronous emergence of the first generation of flies for the new season,2 regardless of exactly when the larvae were deposited.

If chemical treatment is applied to sheep before flies emerge at the start of the fly season, sheep are essentially removed as a resource for the propagation of the fly population when the first generation appear. As emergence is relatively synchronous and the first generation is typically small, this can have a significant effect in reducing fly numbers and the risk of flystrike for the rest of the fly season.

Optimum fly control will also depend on farm management practices. Integrating early season treatment with strategically-timed shearing or crutching will further reduce susceptibility to flystrike and contribute to reducing fly numbers3 – remembering to be conscious of wool withholding periods.

CLiK™ Extra contains dicyclanil, a potent insect growth regulator (IGR). These products provide long lasting protection from flystrike and break the lifecycle – ideal for strategic control.

On-farm research into early season treatment identified that chemicals used for this purpose have to be relatively long acting to suitably cover the full period of spring emergence.2 The availability and ease of application of insect growth regulators to protect sheep for extended periods makes them ideal for this purpose.4

CLiK™ Extra contains 30% more dicyclanil than CLiK™ and sets the benchmark in flystrike prevention. CLiK™ Extra has a registered protection period of up to 29 weeks, ideal for early season treatment – even in years with a late or delayed start to the fly season.

CLiK Extra is indicated for use on sheep either off-shears or with any length wool, with a meat withholding period of 21 days, wool withholding period of 3 months and ESI of 63 days. CLiK Extra is supported by the Elanco technical and sales teams, who are available to provide advice on fly prevention for the upcoming 2021 season.

Please contact Elanco on 1800 226 324 or go to

Always read and follow the label directions.  Good agricultural practice is essential for optimal blowfly strike prevention.

For more stories from the second edition of Your Rural Success Magazine go to

  1. McKenzie, J.A. & Anderson, N. (1990). Insecticidal control of Lucilia cuprina: strategic timing of treatment. Aus Vet J 67(10):385–386. 2. DeCat, S. et al. (2012). Survival over winter and spring emergence of Lucilia cuprina (Diptera Calliphoridae) in south-eastern Australia. Aus J of Entomology 51:1–11. 3. Larsen, J.W.A. et al. (2012). Prevalence of breech-strike in mulesed, clipped and unmulesed Merino hoggets in south-eastern Australia. Aus Vet J 90(5):158–166. 4. Bowen, F.L. et al. (1999). H.R.: Long-lasting prevention against blowfly strike using the insect growth regulator dicyclanil. Aus Vet J 77:454–460. PM-AU-21-0245




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