Do not use insecticides prophylactically, can create resistance.
Have you looked closely?
Check them over real well for mites and/or lice.
Google images of lice/mites and their eggs before the inspection so you'll know what you're looking for.
Part the feathers right down to the skin around...
Worked here for lice. Need to retreat every 7 days until you see no live lice.
Not a good idea, can cause resistance....then it's worthless if you really need it.
Infestation of what...lice?
Mites would be a different story.
Good post about mite ID by Lady McCamley:
https://www.backyardchickens.com/threads/my-chicken-has-mites-now-what.1273674/page-2#post-20483008
No withdrawal.
They look like the lice eggs I've seen.....but I've never seen mite eggs.
I use the headlight at night to see the bugs themselves, gotta be quick tho, as they are.
With lice, just treat the birds.
Roost mites are the ones you need to douse the whole coop,
because they don't live on the birds
If you're seeing lots of eggs, might be good to do 3 treatments 7-10 days apart.
Just keep checking for live bugs.
Part the feathers right down to the skin around...
First find what kind of mites, here's a good run down:
https://www.backyardchickens.com/threads/my-chicken-has-mites-now-what.1273674/page-2#post-20483008
Treat all the birds, then treat again in 7-10 days.
They can get on humans, but can't live on us for long, take a shower after treating.
I just give a few squirts around the vent and neck, under each wing and on the belly.
Make sure you get it on the skin.
Repeat after about 7 days, then check in another 7 days and if any live lice treat again.
Don't need to treat coop unless you have Roost Mites.
Mites are probably all dead, no need to treat further...but...Scaly Leg Mites can damage the scales, it can take weeks to months for them to grow back, if they do at all.
Sorry, no quick end.
Common sense tells me not to spread DE all over the place, it doesn't kill bugs anyway. If there are...
Yes, I understand how it works, most of it spreads over the skin rather than entering the bloodstream, I use it on my dogs....just don't think it would work the same on birds as mammals( @Sue Gremlin would know) ....and don't want it in my eggs.
Not sure who you were addressing, but....
Wouldn't want fipronil in my eggs.......and it wouldn't work to treat the coop if there were roost mites involved.