TIMING IS CRITICAL FOR EFFECTIVE LICE CONTROL

Courtesy Elanco

WITH a plethora of chemicals and application methods to choose from, sheep and wool producers have been reminded that treatment with an off-shears lousicide remains one of the cornerstones of strategic lice control for most producers.

Elanco Sheep Brand Manager, Dave Rathbone, says while new oral treatments can be administered to sheep with any length wool, it’s important for producers to focus on strategic outcomes rather than convenience.

“There’s no doubt that producers have welcomed the flexibility of being able to treat lice at any stage of the wool growing season,” he says.

“However, the focus needs to be on when is the most effective time to control lice, rather than when is the most convenient time for you to treat sheep.

“Saturation dipping in short wool sheep remains the ‘gold standard’ for lice control because sheep are completely immersed in a knockdown chemical at a time when the lice population is at its lowest on the animal.

“Shearing physically removes approximately two thirds of the lice population with the fleece. Treating off-shears with a pour-on lousicide is a popular and very effective method of controlling the remaining adult and juvenile lice that remain on the animal.

“Long wool backline treatments are ‘salvage’ treatments that will reduce the lice burden and minimise fleece derangement until shearing.

“Follow-up treatment with an off-shears or short wool product is recommended.”

Dave stresses that good management is required to keep sheep lice-free from one shearing to the next.

“There is no ‘silver bullet’ when it comes to lice control,” he says.

“If you don’t muster all your sheep; if you don’t apply your chosen product correctly; if you don’t treat all your sheep; if you don’t maintain good fences; if you don’t quarantine or treat introduced sheep . . . then your sheep are still going to have lice.”

It’s also important that producers adopt and implement best management practice to protect the efficacy of all available effective chemistry.

“Many Australian sheep and wool producers have relied upon the same chemistry for sheep lice control for more than a decade,” Dave says.

“Industry guidelines discourage the consecutive use of lousicides with the same mode of action to prevent the development of resistance. ¹

“Put simply, if you’ve been using the same chemical group continuously, then it’s time to rotate to another chemical group – and then rotate again the following season.

“This advice applies equally to all products and to all chemical groups.

“Likewise, it’s important not to use the same chemical group for lice control and blowfly strike prevention during the same wool-growing season.”¹

“While there is no known field resistance to spinosad or thiacloprid, the active ingredients in Extinosad^™ Pour-On and Viper^™ Pour-On, respectively, it’s important that we keep it that way for as long as possible.

Extinosad Pour-On and Viper Pour-On are excellent rotation partners for lice control.

Extinosad Pour-On provides rapid knockdown control² of lice with minimal impact on your management or marketing options.³

This user-friendly, water-based formulation has nil wool WHP and 21-day ESI when applied up to 7 days off-shears or to unshorn suckling lambs.³  

It can also be used to control lice on sheep with long wool.

Viper Pour-On contains thiacloprid, which is up to six times more potent against sheep lice than imidacloprid, in a convenient, water-based formulation.^4,5,6

Viper Pour-On also provides rapid knockdown⁵ of sheep lice and protects against re-infestation for four weeks when applied within 24 hours of shearing.³

Extinosad Pour-On and Viper Pour-On are the only lousicides that come with a six-month, off shears lice-free guarantee.⁶

Elanco guarantees that if either product is used in accordance with the label directions and best practice lice management guidelines, no lice will be detected on sheep six months after treatment off-shears.

“If lice are detected and we are satisfied that you have complied with the terms

and conditions, Elanco will provide a suitable treatment to control lice on the affected sheep,” Dave says.

“This guarantee is just another example of how Elanco is committed to helping its customers to obtain best results from their investment in quality animal health solutions.”

Elanco employs a team of regionally-based advisors who provide a range of on-farm services, including strategic lice control programs, best practice guidelines, application training and Power Doser servicing.

Always read and follow the label directions.

Good agricultural practice is essential for optimal lice control.

For more information, please contact your local Elanco representative or Elanco Customer Service on 1800 995 709, 8 am–5 pm EST Monday to Friday.

Withholding periods. Extinosad Pour-On (Off-shears and suckling lambs): Wool WHP: Zero (0) days. MEAT: 14 days. ESI: 21 days. Milk WHP: Do not use on ewes that are producing or may in the future produce milk that may be used or processed for human consumption. Extinosad Pour-On (Long wool): Wool WHP: Zero (0) days. Meat WHP: Zero (0) days. ESI: Zero (0) days. Milk WHP: Do not use on ewes that are producing or may in the future produce milk that may be used or processed for human consumption. Viper Pour-On: Wool WHP: 6 months. Meat WHP: 42 days. ESI: 56 days. Milk: Do not use on ewes which are producing or may in the future produce milk that may be used or processed for human consumption.

References: 1. James, P. (2013). Preventing resistance in sheep lice, liceboss.com.au (AWI, Sheep CRC). 2. Levot, G. (2008). Speed of action and in vitro efficacy of spinosad against sheep body lice, Bovicola ovis, resistant to pyrethroid, organophosphate or insect growth regulator insecticides. Aust J Ent 47:251-255. 3. Refer to registered labels. 4. BAH Laboratory Study 6106008 2006. 5. BAH Laboratory Study 6108010 2008. 6. BAH Laboratory Study 6105020 2005. 6. Visit extinosad.com.au or viperpouron.com.au for terms and conditions.

Power Doser™ is a trademark of Genesis Industries Australia. Extinosad Pour-On contains 20 g/L spinosad. Viper contains 10 g/L thiacloprid. Extinosad™, Viper™, Elanco and the diagonal bar logo are trademarks of Elanco or its affiliates. ©2026 Elanco or its affiliates. EAH25003. PM-AU-26-0090.