Slap-dash approach waste of time for lice count

Speaking at the Healthy sheep are happy sheep workshop, he said producers could not be too careful when applying pour-on lousicides, as a slap-dash approach was "a waste of time".

"If you don't take the time to ensure you're applying it properly, then it's a waste of a dose and a waste of money," Mr Aust said.

He said post-shearing applications were most effective, with producers preferring knockdown products rather than slow-acting chemicals.

"The big interruption to the life cycle is shearing, and shearing will remove up to 80 per cent of the lice," he said. "The lice remaining on the shorn sheep are at their absolute lowest ebb because their environment has been taken away, they are susceptible to UV and heat, and that's the best time to hit lice if you're looking to control them in the flock."

He advised producers to ensure boundary fences were well maintained to stop stray sheep wandering in, and encouraged producers to consider dipping options.

"We strongly favour the use of dipping in the mix again. Saturation treatment is the most thorough way that you can treat an infestation," he said. "With a pour-on, the chemical has to find a louse to kill it, whereas after dipping the sheep is absolutely saturated and lice can't hide."

He also warned producers against using consecutive applications of lousicides with the same mode of action, and cautioned against the use on ewes nearing lambing.

"Pregnant ewes shouldn't be treated within six weeks of the commencement of lambing," he said. "The reason for that is that the chemical takes a while to work. In that time, the lambs can be born, and when the lambs are suckling, lice can be transferred from the mum to the lambs.

"Those lambs become infested, and once the effect of the chemical has worn off and has dropped below the lethal dose level, those lambs can then re-infest their mothers."

He said lice infestations were a disaster for wool production, knocking an average of $10 a head off the wool clip.