Lice on my backyard flock
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Wood ash and DE can help with prevention, but once you actually see bugs I honestly recommend Poultry Dust with permethrin/pymethrin.
There is no egg withdrawal. Simply dust each bird individually and reapply in 10 days. You may have to do it 3 times to get rid of the infestation.
If you put the dust in a nylon stocking, you can dust like a powder puff. The other option is to put it in a small garbage bag and "shake and bake" the bird.
Clean your coop well, get rid of the bedding, and sprinkle Poultry Dust liberally.
If that doesn't work, then you may have to go to stronger measures like Ivermectin, but chances are, if you are diligent and stay the course reapplying appropriately, you'll get on top of it.