Help. The lice will not die.

[here to stay]

I have tried a synergized pour on- 4 treatment every 10 days.  Oral Ivermec Plus repeated after 10 days.  Ivermectin Paste orallly at 3 times the weight dose.   But they never disappear totally and seem to return within 2 weeks of treatment.

I was going to spray the sheds but I  got to thinking that they have lots more hang outs than that, like the giant log and the big stump.  

Any suggestions?

[here to stay]

I could spray with lime sulfur. I did that once with a goat who had manage.

[Bear Foot Farm]

I'd use this for the animals and the premises:
happyjackinc.com/our-products/flea-tick-control/kennel-dip-ii/

Kennel Dip II

Kennel Dip II is a water-based, environmentally friendly concentrate that provides 30-day residual control of fleas, ticks (including deer ticks), lice, mange mites and stable flies. Effective and economical, it can be used as a dip, a sponge on or a premise spray. Compare Kennel Dip II to other formulas and spot-ons. Mix 1/2 oz. per gallon of water as a dip or sponge on or 4 oz. per gallon of water as a premise spray.