Off-shears or short-wool application remains a key strategic time to achieve effective lice control, according to Elanco senior brand manager – sheep, Dr Kathryn Humphries.

Dr Humphries says depending on which method of application is selected, it is advisable to treat sheep either off shears or in short wool (2–6 weeks post shearing) when the lice population is lowest.

“Shearing removes about two-thirds of any lice present in the fleece, so treating when the lice population is at its lowest is a good idea and maximises the chance of achieving effective lice control.

“Don’t wait until sheep are visibly lousy in long wool because by then the damage has already been done.

“The majority of products registered for the control of lice in sheep with long wool are essentially a ‘salvage’ treatment to reduce the lice burden and minimise fleece derangement until the next shearing.”

Dr Humphries said Extinosad Pour-On and Viper are two popular choices for off-shears lice control.

“Extinosad Pour-On is a flexible option for off-shears application. It delivers rapid knockdown control of lice and is backed by a six-month, lice-free guarantee when applied off-shears.

“It has no withholding period for wool and a 21-day ESI when applied up to seven days off-shears or to unshorn suckling lambs, so it has minimal impact on your marketing options.

“Extinosad Pour-On can also be used to control lice on sheep with long wool. It contains spinosad and is an ideal rotation partner for neonicotinoid chemistry.”

Dr Humphries says Viper provides powerful knockdown control of lice with the assurance of a protection period.

“Viper provides four weeks’ protection against reinfestation when applied within 24 hours of shearing and, like Extinosad, is backed by a six-month, lice-free guarantee when applied off-shears.

“Viper contains thiacloprid, next-generation chemistry which is up to six times more potent than imidacloprid, according to three separate previous commercial studies.

“And like Extinosad, it’s a water-based formulation.”

Dr Humphries said Elanco supports the adoption of best management practices to protect the efficacy of all effective chemistry.

“All lice treatments should be applied as part of an integrated pest management program, including good fencing, mustering, shearing and application technique.

“Do not apply the same mode of action consecutively.

“If consecutive use of the same mode of action is required, careful attention should be paid to achieving eradication after treatment.

“Likewise, do not apply the same mode of action for lice control and flystrike prevention in the same season.

“This means imidacloprid should not be applied for the prevention of blowfly strike if neonicotinoid chemistry was applied to control lice earlier in the same wool growing season.

“Producers should also consider the impact of using lice control products that contain abamectin in their strategic drench programs in terms of resistance management.”

Dr Humphries said good agricultural practice is essential for optimal lice control. Always read and follow label directions.