This morning i found one of my hens in a bad mood. She looked really sad. I checked her, and i found bugs on her. I think they are louse. Last time i found them they were greenish in colour. This time their back was a bit brownish. I used a powder that has pyrethrin and piperonyl on them, and i sprayed inside the coop with an anti-parasite agent. It is the third time i do this in such a short period (~3 months), and this is either due to the straw i have, or the powder is not effective. I used the anti-parasite agent on the straw pile i got, and on the nests too. In case i still got a problem that probably means that the powder is not effective. What can i use as an alternative then? Any ideas? Thanx in advance.