Ordinary poultry louse powder containing permethrin worked fine when I bought new pol hybrids without checking them first. I think I used it 3 times, about 3 weeks apart. On the final application most of them had none but I treated them anyway to be sure. I do them at dawn by taking them out of the henhouse one by one before the pophole has opened. I wear my mucky waterproof trews and jacket and take a stool and old handtowel with me. I wrap the bird in the towel with her head peaking out then I sit on the stool with the bird on her back on my lap, head away from me. Using one hand on the towel/bird I use the other hand to dust around vent and oxters.