If you can see them you have them!, try squishing them with your finger if they leave a trail of blood then this is red mite !
Your hens won't show any symptoms until the are really badly infested, so act now !
I am fighting a battle with them at the moment, I have scrubbed out my coup with Jeyes fluid, let it dry then I dusted everything with diatoms (an organic treatment which is supposed to be really good) I also dusted each Hen, but only this morning I saw more, not in the areas I had done already but some I had missed like the underside of the floor !! so I have just finished powdering everywhere again!
When the infestation gets bad the amount of blood sucked from your hens starts to drain their energy and they lay smaller or less eggs, eventually this can lead to sickness and even death! This is a graduall process and sometimes goes un-noticed so keep going and good luck !
Check this out for information
http://www.worldwidepoultry.co.uk/diatoms.php
