As @aart said. Maintenance is the best prevention. If you use most anything on a regular basis as a prevention, pests will became resistant to the treatment. I do keep permethrin on hand because it works for me. If I notice any lice or mite, I usually do 3 or 4 weekly treatments spraying inside the coops thoroughly, concentrating on cracks and crevices in the coops where mites can hide. Most products do not kill the pests eggs so weekly repeated treatments are needed. There is no egg withdrawal period with permethrin. If it doesn't work for some people then most likely they are not mixing the correct amount with the water. A benefit here is that it also keeps the flies under control. Everyone's situation is different. I use the concentrate and mix it in a gallon sprayer because I have several coops and if I treat one coop, I'm going to treat them all. I like the wand on the sprayer to reach into hard to get to areas. I also use permethrin poultry dust in the nest boxes. When I check my birds, I usually do it after they roost. I wear a headlamp so I have both of my hands free to check over the birds. I don't treat if there is no pests. Everything is available at my local TSC. Good luck...
Organic Gardening...not sure it really works there either.
