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Tasmania worms, flies and lice update - February 2021

Tasmania WormBoss Worm Control Programs

Tasmania WormBoss Drench Decision Guides





Perth: Paul Nilon, Nilon Farm Health (

Since the last report the northern half of the state received rainfall of between 200 and 100 mm. The south has remained relatively dry. Although pastures are dry on top, many have a green bottom and worms are cycling like Cadel Evans down a French alpine hill.

As discussed previously sheep in all areas on perennial pastures will need a second ‘summer’ drench, perhaps a third. Now is the time for the second if it has not already been given. The third can be given in April if needed. You must expect that the cool summer with plenty of ground cover will make for a wormy autumn and winter, so be prepared.

Risk Management of Lice: A client whose sheep were diagnosed with lice last year asked what he should do this year. He was shearing lambs immediately and his ewe flock in April. Should he treat the lambs and ewes off-shears at their respective shearings? So, the Q&A went like this:

  • Have you seen rubby ewes or lambs? No
  • Have you formally inspected for lice? No
  • Have you had incursions or excursions likely to have placed you at risk? No

Without evidence of lice, and no known risks, there is little reason to treat lambs off-shears. Notwithstanding his concerns about lambs’ capacity to get back to their mothers, if he treated the lambs with something with a short export slaughter interval (ESI) it is likely the ewes would reinfect the lambs. Moreover, he is a lamb trader, and those coming in present the biggest risk. So, the advice was:

  • Don’t treat the lambs.
  • Inspect the ewes close to shearing and make a decision on whether to treat them based on what you find.

Because his is a prime lamb enterprise with wool used for oil tanker hawsers the sky will not fall if we get it wrong and the no-treatment policy turns out wrong. When all is said and done the biggest risk are the trade lambs. Their risk is present whether we treat now and in April, or not.

The advice from the merchandiser: “Treat them to be sure”. Sure of what you may well ask.

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