As everyone will very well notice, this is my first post. I have lurked here for several months, if not years. In October of last year, my wife and I added 6 chickens to our lives; 2 Buffs, 2 Barred Rocks and 2 Araucanas. With the aid of this site I have navigated my way through several issues with the chickens, from coop size, to run size, to groundcovers, etc.
Long story short, my chickens are aggravating the feathers around their tails, giving them the effect of appearing fluffy. I have attached a photo to better explain this. Now as a brief history, originally I had straw in the run, even knowing that some recommended against it as it could harbor mites and/or lice. As soon as this epidemic struck, I removed the straw from the run, dusted the chickens with Poultry Dust, cleaned the coop thoroughly, dusted the coop with Poultry Dust and then redusted the chickens a week later. This was a week ago. During the last week I have added DE to my arsenal and added it to every known dust bathing location I could find. I haven't seen any of them pecking each other and I do notice them itching from time to time (I dunno how much is normal). Despite being confident this is a lice/mite infestation, I have thoroughly inspected the girls and I am unable to see anything.
Has anyone seen this before? Any ideas what I should do? Could it be heat here in Phoenix? My last resort is Ivermectin, but I wanted to avoid anything they might absorb internally. I am sure I probably left out some pertinent details, I will be checking back frequently and will respond accordingly. Thank you everyone for your help.