The kerosene soaks into the wood and kills all critters that are on/in there and the linseed oil seals the wood. A lot of people use Seven dust in their coops. It's safe and effectiive. We put it on the ground and then put the wood shavings over it.
This has been a horrible year for bugs. So...
According to "Storey's Guide to Raising Chickens" new edition by Gail Damerow You should clean the roosts like this: brush roosts monthly with a mix of 1 part kerosene to 2 parts linseed oil and at the same time coat their legs with vaseline.
I just went through my coop and did that. I also...