The performance of all shower dip chemicals for sheep lice can vary depending on the active chemical and the conditions under which they are used.
Department of Agriculture trials have indicated that the wettable powders coumaphos and magnesium fluorosilicate were less effective at eradicating sheep lice than were synthetic pyrethroid and organophosphate dipping chemicals.
However, failure to eradicate sheep lice may be the result of several factors, many of them related to management.
Higgs, Tony and Love, Bob
"Choosing shower dips for sheep lice,"
Journal of the Department of Agriculture, Western Australia, Series 4: Vol. 34
, Article 6.
Available at: http://researchlibrary.agric.wa.gov.au/journal_agriculture4/vol34/iss3/6