I had someone recommend to me to dip my chickens into a big container of water full of different essential oils etc.
Oil floats on top of water.
I'm guessing they mean the oil MUST cover completely to
suffocate said parasites... the way we used to use mayonnaise to treat our head lice as kids (it had to stay on overnight.
The essential oils... basically just smell good, and ANY oil would work... I would think. Seems like the container of water would be a messy nightmare though. I personally would consider using one of those oil pump sprayers that's supposed to mimic the "pam" stuff, but with whatever oil you chose. Anybody who has ever dipped a chicken in water (IE processing to pluck feathers) KNOWS things don't just easily go to the base of the feathers/skin... the reason why it takes several moments of dunking and swishing to get it right for plucking. Just going through the thought of my over thinking brain that tries to figure out the core of EVERY possibility.
Yes, it makes sense that having mites, could cause more risk from cocci... or anything else really. I don't think it will make it appear sooner than it's standard life cycle though... just *possibly* hit harder once symptoms do present. And even then some chicks will still have stronger immune systems than others. Some will fight off the mites better from the very get go, oddly enough.
Some people do mistake a few dry raised scales on the legs with mites. In stead of realizing that they are skin that does get dry, age, and fall off to be replaced. My vet said it should look like keratin growth coming out from under the scales. And those mites are microscopic so will NEVER be seen by the naked eye, just their signs of them. Yes leg mites CAN be treated by suffocation... but since you already did the Ivomec, I think that should take care of them. On the babies legs you might rub vaseline, crisco, or other thick/safe to use product. Not sure if the oil will be think enough to create the desired effect... but, ALSO here to learn!
Please note... DE is rendered ineffective when wet... and oil will make whatever is still on their skin wet. I don't know if the micro cutting shards get their sharp edges back once they dry again or not. For me, I skip the micro cuts... if it works against bugs, it works on my skin too and that of my chooks in their airways when inhaled. I don't my birds using energy to heal microcuts day in and day out. Hopefully seeing the fun your hen was having in the dust and respiratory response of the chick will allow you to reconsider as a future NON option. Not saying it doesn't work (though I think it does very limited)... just that there are POSSIBLY better ways. Also, it will work better in dryer environment than mine... we often have 85% humidity and things don't "dehydrate" that fast in humid areas.
I'm not sure how effective spraying the yard with permethrin may or may not be depending on the pest and your weather. You may be hoping to catch an egg that fell off and is hatching or something since these kind live ON the bird? Verses the red mites I have seen under wood in my yard. I do use it in my coop a little if I need to treat the birds.... which by the way... means you have wildlife not that you are a terrible keeper.
Not sure WHAT symptoms your babes were displaying that got better after the Corid... But for your informational purposes... ONLY 1 of the 9 (or 11 depending on source) of strains of cocci will present as blood in the stool. And even then not every single poo will be bloody even from the bird that just made a bloody poo in front of you. And not every bird will display ALL of the symptoms of an illness, which is sometimes what makes it so hard for us to discern what is really going on. So we make out best decision we can according to what we see. Especially in chickens, SOO many things can present very similar to so many others making it yet even harder for us.
So if you feel like you should treat for something even though you don't see ALL the symptoms... you may well be right!
It's OK to be a crazy chicken lady... you're in good company!
I think it's awesome when peeps are willing to go the extra mile or twenty when needed for their pets.
Skip the suggestions of do this and do that like an oil water bath. If your birds are going top be exposed to the permethrin anyways... just use it ON the birds and kill the bugs instantly... I've seen it work in person! Since I use the spray... it's as simple as a small squirt right below the vent, in each wing pit, and to the nape of the neck (since head lice don't leave the head). All with feathers parted and squirt bottle close to the skin. It's actually waterproof once it dries and continues to work for at least three weeks on many things to catch new hatching bugs. I haven't used the powder because (one I didn't know it existed) the ease of spray that doesn't shake out for me or them to breath in the poison has been awesome. I have sprayed myself many times though, so not saying I get zero exposure. So far me nor any of my animals have had a reaction to it since I started using it to combat mosquitoes on my goats and dogs last year or the year before.
I haven't done a close inspection for mites since dusting
If you SAW bugs... they weren't scaly leg mites.
I'm sure your week old chick will recover just fine from it's dust storm the other day.... Pics welcome!
That isn't even approved for use in poultry and is a serious cattle dewormer. The ONLY type of mites it should be used for are scaly leg mites and depluming mite. Both of which are microscopic, systemic feeders making the permethrin less effective.
I just don't get it. 
