So I have been sitting on this for a while - I wanted to see if it really worked as well as it seems to have done, before sharing my experience with you all.
A bit of background:
Last year I had a dreadful infestation of red mite. I ended up spending about 6 hours a week cleaning and re-cleaning my chicken coop with every single powder, potion and spray my local pet shop could offer. It got the numbers down, but it never really cleared properly. Then winter came and I forgot about it for a while. Fast forward to June of this year, and I'm noticing them appearing at the perch ends again. I do a full clean, spray insect growth inhibitor, throw Diatameous Earth everywhere and assume that should stop it getting any worse. Imagine my dismay 10 days later after a holiday to find that in that short time, I have another full-on infestation on my hands. Every nook, cranny, gap, wood-joint has mites on, in and over. I touch the coop and my arm is covered in minutes. I had a serious discussion with my partner about getting rid of the chickens. The thought of spending three days a week cleaning the chicken coop all summer again is more than I can bear.
Having established that the pet shop has absolutely nothing they can sell me that actually works (most of these sprays and potions at best reduce the numbers for a week, but at worst do absolutely nothing at all), I raid my kitchen cupboard for anything that might be of any use for this battle I'm losing yet again.
Then I find it. In a radioactive-yellow spray bottle, gathering dust is a bottle of Cif Oven Cleaner - It has all sorts of warnings on the back about toxicity to just about every living thing on the planet. I figure that I never clean my oven, so I may as well find another use for it.
I was initially dubious about using it in my chicken coop, so I thought I'd just test it on a little area. I found a heaving pulsating cluster of red mite and sprayed the tiniest bit on.
Much to my ecstatic delight, they all stopped moving within about 5 seconds. Then for my continued entertainment, they started melting into this kind of greeny ooze. I never knew pest control could be so satisfying - Time for some full-on chemical warfare...
I sent the chickens off up the garden with their drinkers and feeders, and locked myself in the chicken run. Being careful not to let any drop through the coop and onto the run floor, AND WITH GOGGLES AND RUBBER GLOVES ON (you do not want the wind catching this stuff and blowing it in your eyes) I sprayed oven cleaner over every surface, into every nook and cranny, and let the caustic kitchen product take effect for a few minutes. Then I cleaned it all with fresh water over about 30 minutes (I had to change the bucket of water multiple times, until I was sure there was no residue left on any surface).
I reassembled and dried my chicken coop, lined it, then DE'd the hell out of it. I also threw ash from my barbeque in the nesting boxes too, and threw more in day after day for about a week.
For the next 6 weeks or so I kept checking day after day. No sign of red mite at all!!! Plus my chickens looked happier and healthier within just 24 hours or so.
They have JUST started coming back now (we are now 3 months later), but a quick squirt of neat Cif oven cleaner on the affected area, wait 20 seconds, then wipe away with sponge and water kills them dead. Chemically I don't know how it works, but I assume it is also eating through the red-mite eggs too. The great thing is that via "capillary action" it also penetrates the tiny gaps in which the mites live which you simply cannot do with diatameous earth which I guess is another reason that it is so utterly effective.
A WORD OF WARNING THOUGH: I AM NOT RECOMMENDING FOR A MOMENT THAT YOU USE THIS METHOD TO CONTROL RED MITE YOURSELF - SIMPLY TELLING YOU MY EXPERIENCE. Oven cleaner is highly caustic, and probably not very good for chickens to ingest. However, a slow death from anaemia brought on by blood sucking insects isn't very good for chickens either which is why I went for a last resort control method. Anecdotally, I can tell you that after 3 months, my chickens have not died and nor have I. And at the end of the day, oven cleaner is designed for ovens - where we cook food, so while you wouldn't want to start drinking it out of the bottle there must be a degree of safety if a trace or two does remain on the surfaces you clean with it.
As I say, I DON'Tt suggest you copy my method - you have to make your own call on what you think is best for your pets. But I'm not wasting my time with the rubbish the pet shop sell me anymore (except DE as a preventor). My chickens look the happiest they've been in ages, and I sleep easier at night, knowing that they are sleeping comfortably too.