Geeeze, from what you are describing, absolutely you have a severe infestation of northern mite. When the skin of the chicken has these awful scabs, that is a severe infestation. I saw that bad of an infestation on only one of my birds last year. The others had the mites, but the one had them horrible. And that is what I really noticed, which really alerted me to look very closely. Those scabs on the back end, around the vent area and extending down the legs. Do not beat yourself up. Mites can get hold this time of year very, very, very quickly and can be in explosion mode in no time at all.
When I noticed the scabs on the bird in question, I knew that something was wrong and I delved and looked very deeply. I pulled out all the feathers that I could see that had enormous clusters of mites, millions of them I would venture. I am thanking my lucky stars that I did not have any other birds with this severe of an infestation. Some get them worse than others. Those feathers that had long clusters of thousands of mites on each feather were burned in our barrel. The bird looked rather bare after I was done with it.
Upon checking the other birds, I saw mites, but probably 1/100 as bad as this one. I used a product, there are several that are very effective. I am sure you have read the threads by now that Shipperkesue has bumped. Very informative and there are lots of options.
If I were you, this is what I would do right now. Get the louse powder. I believe it is made by Dominion and get that dust on the back end of the chickens. You might find mites elsewhere on the bird, but for now, focus on the area below the vent and do the belly of the bird too. also do all the bird whilst you are at it, but these mites really like to live in the ventral areas and below. This will put a stop to the lice pretty quickly. Dusting is very effective. I used dusting powder on occasion and believe in it totally. I don't trust diatomaceous earth, maybe it works, maybe it does not, I think for a maintenance schedule it is good, but if you have a bad infestation and clearly sounds like you have, you must get out the bigger guns and reach for mite control applications.
Another thing to look for is what appears to be dirty feathers on the back end, extending down the back end to the belly. Pull one of those feathers and you will see that this is not dirt that you are seeing, but thousands of mites that are clustered. They will appear as red, black, grey dots, depending on how much feeding they have been doing.
This is horrible. And I know what I am speaking to, because I have been there, done that. I am not embarrassed either to come on open forum and confess. There will always be mite issues. Mites can be brought in from the wild birds that may come near you, places the chickens traverse to, anywhere. Many are hosts to mites, particularly the northern fowl mite, it is not exclusive to fowl as we know them, our chickens, I speak of. I have had mite issues off and on and thought that I had them eradicated. Don’t ever think that you do. As I said, they can come in on the wild things, not just the tame things.
At present, I do not believe I have mite issues. At present. That does not mean that I will not in any time in the future. I use preventative measures and it is time for a dose of product on my birds. I am in check mode tomorrow. I checked 3 buff Orpington gals that are broody, sitting on eggs and they are mite clear. That is good, as the broody hen is the perfect incubating environment not only for eggs, but the mites as well. They looked clean as clean could be. The cochin coop is my tomorrow job. When any bird leaves our farm to go to someone else, they are ALWAYS treated for mites. That is something I do and will always do. I would never take a chance to have an egg or two from a louse or a mite leave here to go elsewhere. This is part of my control measure.
So...first off. Get some louse powder. Dust. Suggestion is to hold the bird between your legs as you are sitting down and place that bird upside down. Chickens are pretty calm when in this position. Look closely. If you see those clusters of mites on the feathers I speak of, remove those feathers and put in a bucket for the disposal, however you dispose. Then proceed to get the dusting powder on the belly and ventral areas. Once you have done this, you will have some time to get further chemicals to stop further mite stuff, or dust again in a while, there will be eggs that will be hatching. I honestly do not know if the dust stays and kills eggs, maybe someone can speak to that, but I am just not sure.
I had a couple of chickens that I had to look after for awhile for someone. Before I let them go out of the container that they had come in, I checked them for mites and lice. They had both. I dusted immediately and also gave a dose of ivermectin. Double dosing, but it is what it is. A few days later I checked and the birds did not have any evidence of crawlies. I checked just before the birds left, which was about 3 weeks and still no evidence of mites or lice. The products used in conjunction eradicated mite and louse. The person whose birds I was looking after had been advised of what came on the birds. She cleaned out her chicken houses, applied both products, as I instructed her and the birds went back home clean from my place and to her clean home. I am sure she is 100% mite and louse free now too. And I was pleased that she listened and reacted so quickly. You don't know you have bug issues, unless you look. AND...assume that you do.
These things happen. Again, do not beat yourself up, nor think you are a bad chicken keeper. Because you are not. Nor is anyone that has insects such as these. This is part of what we are exposed to from the wild and the tame, we just need to do the best we can to keep on top of things. A good time of year for these things to be brought to the forefront of our minds, so we can have happy chickens (and happy humans too). Oh when you are dusting for mites or lice, or whatever, you are handling your chickens in these ways. Undoubtedly you will be bothered yourself and feel crawly all over, smiling. You will want to shower and probably launder your clothes immediately, smiling again. Have a wonderful day, CynthiaM.