This most probably is red mite, Hog. Have a look at these links to Poultrykeeper
How to spot red mite http://poultrykeeper.com/red-mite/how-to-spot-red-mite
And http://poultrykeeper.com/red-mite/red-mites
For information about what they look like and how to deal with them.
They are very difficult to get rid of once they've arrived in large numbers, especially in a wooden house. Problem is, they will have laid eggs in tiny cracks in the wood, or under the felt of the roof if your coop has this kind of roof, and these will hatch even when you've nearly got rid of the adults, so you have to repeat the treatment every few days to keep them under control. Bit of an uphill battle, I'm afraid.
Yes, creosoting the inside of the house will help, but you need to use the old fashioned, original form of creosote, from an agricultural merchant, not the less toxic kind you buy nowadays in DIY stores.
One more weapon you could use is to get some Red Stop and add it to their drinking water. This makes the hens blood taste nasty to the mites so they starve. Its organic and harmless to the hens and doesn't affect the eggs. You only need a few drops per drinker, so a bottle goes a long way.
See http://chickens-for-sale.com/new-herbal-poultry-red-mite-control/
19
