Hall C A
Aust Vet J. 1978 Oct;54(10):471-2. doi: 10.1111/j.1751-0813.1978.tb00289.x.
A synthetic pyrethroid, cypermethrin (NRDC 149), showed activity in killing lice (Damalinia ovis) in the fleece of sheep at concentrations as low as 1 ppm in a dip. In addition concentrations of 5 and 10 ppm showed a persistent effect and prevented reinfestation from contact challenge sheep for 7 and 19 weeks respectively.