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Victoria worms, flies and lice update - November 2019

VIC WormBoss Worm Control Programs

VIC WormBoss Drench Decision Guides





Hamilton: Andrew Whale, Livestock Logic ( and Lexie Leonard, Livestock Logic (

  • Monitor weaned lambs closely for the 6 weeks after weaning
  • Re-test worm egg counts 4 weeks after weaning
  • Generally, worm egg counts are low in the Hamilton region

The good spring continues in south-west Victoria. While there has been a slightly below-average rainfall for spring, the cooler temperatures have been keeping pastures fresh. The majority of properties still have good quality feed into November with good lamb growth and low worm burdens expected to continue. 

Coming into December, producers should focus on the timing of their summer drench. If you have not done a Drench Resistance Test (DrenchTest) in the past 3 years now is a good time to identify mobs that would be appropriate for testing. Worm egg counting (WormTest) of mobs allows for the precise timing of summer drenching. If done correctly, the first summer drench will reduce the need for a second summer drench, decrease pasture contamination for next autumn and minimise any production loss. Worm egg count results coupled with visual assessment of faeces, gives the best indication of when it is time to drench. 

High egg counts in mobs need action immediately, while low egg count mobs do not need drenching. They will not have any production loss and will not be causing significant contamination of pastures over summer.

Moderate egg counts do need a drench, but the timing is critical to get maximum effect and benefit. Drench too early (loose faeces and spring conditions), and you increase the need for a second summer drench, as there will be larval pickup post-drenching. Drench too late (well into summer) and you allow significant numbers of worm eggs to hatch and larvae to survive the summer in pelleted faeces.

For properties north of Hamilton, monitoring should start now to ensure the timing of the drench is effective. Properties south of Hamilton, or where there has been recent rain, will find drenching may not be required for another month. 

There will be an increased fly activity for those who have not already taken action with chemical or mechanical treatments for fly. The early December period, if conditions stay warm, will indicate if the 2019/20 summer will be considered as high risk for flystrike. To date, there have been small levels of fly activity within flocks, but nothing devastating.

For November 2019 state outlooks, please follow the links below:
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