More active UK thread here ~
https://www.backyardchickens.com/threads/uk-member-please-say-hi.655508/
For red mite I use this in the Coop ~
https://www.amazon.co.uk/Net-Tex-Total-Liquid-Concentrate/dp/B003L6I7GO
Change bedding and spray at least every 3 days to kill any eggs that have hatched. As red mite don’t actually live on the birds and only come out to feed on them on a night I tend to concentrate on my coops more. But I do apply pigeon drops to my birds intermittently (it’s not licensed for poultry but a vet friend of mine says it’s ok) ~
https://www.amazon.co.uk/Amazing-Animal-Harkers-Harka-mectin-5ml/dp/B00189JPOO
I too have never been able to find a permethrin spray to actually put on the birds as I believe here in the UK it’s not permitted by the government bodies etc. All permethrin products here state do not apply directly. But I tend to think they can get the powder version on their legs etc from the bedding so how can it be so different??