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Victoria worms, flies and lice update - June 2019

VIC WormBoss Worm Control Programs

VIC WormBoss Drench Decision Guides





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

Livestock Logic advises that by July 1, it will be 7 weeks after the autumn break, and 

  • worm egg counts are expected to rise sharply
  • weaners, lambing ewes and spring-born calves are now at the highest risk of worm infections
  • producers are advised to assess pasture risk as well as stock risk when making drenching decisions

By the end of May, the majority of the Hamilton and surrounding regions had received close to their average May rainfall. A combination of the relatively mild late autumn weather and minimal frosts have been good news for pasture growth in those paddocks without stock. Pasture growth will slow coming into July, and paddocks without a feed wedge will likely stay moderate–high risk for worm pick-up until spring.

The level of worm control achieved in the first half of the year will be very telling over the coming weeks and will have a significant impact on pasture worm burdens this winter. If you haven’t achieved reasonable worm control or didn’t monitor with worm egg counts (WECs) over autumn, it is essential to start now. 

WormTest vulnerable stock over the coming weeks to assess worm burden levels and drenching requirements. At this time of the year, WECs are expected to rise sharply in higher risk paddocks and stock classes; as of July 1, it will be 7 weeks since the “break”. WEC lambing ewes before marking to assess drenching requirements for both ewes and lambs. Lambs under 10 weeks of age very rarely require drenching, and it is always worth testing first, rather than just drenching.  Use caution when putting stock in paddocks used for autumn lambing ewes as these paddocks often have high worm contamination—a WEC of mobs at lamb marking can give a good indication of paddock contamination post-lambing. 

Young stock, both sheep and cattle, are also at high risk and should be monitored closely over winter until the end of August as worm burdens can appear quickly when combined with other stress factors. Over winter, nutritional and cold stress are common factors that when combined with high worm burdens cause production loss and death in young stock. 

Pre-lambing ewes or dry stock going onto good pasture should be a moderate–low risk if given reasonable worm control over the first half of the year. WEC testing all ewe mobs pre-lambing can save a lot of drenching for late winter and spring lambing ewes. Dry stock can be used to help clean up high-risk paddocks over winter if needed.

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