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Use Permethrin based poultry spray to treat the birds and coop.
You will need to completely clean out the coop. I would also use a shop vac to vacuum out as much dust as possible then spray the coop with Permethrin mixed according to the bottle label into a 1 or 2 gallon garden pressure sprayer.
When spraying the coop, pay particular attention to the places where wood meets wood. You don't need to saturate the coop, just coat all the surfaces with a mist of the spray. Put a fan on the coop to get it dry then add fresh bedding and nest box material.
Treat the chickens with the Permethrin spray in a hand squeeze trigger bottle. Part the feathers and spray the skin under the vent, under both wings, on the chest and at the nape of the neck. If it's too cold where you are to spray the birds, you can dust them with permethrin based poultry dust in the same locations. Just ruffle the feather to disperse it down to the skin.
The coop cleanout and spraying and treating the birds needs to be repeated in 7 days and again at 14 days if you have a bad infestation.

Use Permethrin based poultry spray to treat the birds and coop.
You will need to completely clean out the coop. I would also use a shop vac to vacuum out as much dust as possible then spray the coop with Permethrin mixed according to the bottle label into a 1 or 2 gallon garden pressure sprayer.
When spraying the coop, pay particular attention to the places where wood meets wood. You don't need to saturate the coop, just coat all the surfaces with a mist of the spray. Put a fan on the coop to get it dry then add fresh bedding and nest box material.
Treat the chickens with the Permethrin spray in a hand squeeze trigger bottle. Part the feathers and spray the skin under the vent, under both wings, on the chest and at the nape of the neck. If it's too cold where you are to spray the birds, you can dust them with permethrin based poultry dust in the same locations. Just ruffle the feather to disperse it down to the skin.
The coop cleanout and spraying and treating the birds needs to be repeated in 7 days and again at 14 days if you have a bad infestation.