powder .. no better spray, like permetrin or piretroid, they are not toxic and work well
I am presuming you mean in chickens?
For feather lice I use Mitex powder which is finely ground up fossil shells which draw the moisture out the lice. Either apply it directly to the bird or put it where they dust bathe and they do the dusting themselves.
To be honest as long as your hens have access to a dust-bath either their own they create by digging in the soil or one you put in (this could be wood ash, fine sand or dry peat/compost in a tray) then feather lice are rarely a problem. Its when I have broody hens and they sit for 3 weeks or more without dust-bathing I have problems. The lice do live in the woodwork of the coop and emerge weeks later when a new bird is put in. I've had them attack a broody hen and kill her, very sad. I always dust broodies with Mitex now and the chicks when they hatch.
Scaly leg I use vaseline applied liberally to the legs/feed. The scales don't drop off until the bird moults so it still looks bad but the mites die quite quickly, 2 applications a week apart usually does the trick. For feathery leg breeds vaseline is not so good (I have a Brahma cockerel) so I use Spot-on treatment from the Vet if he has scaly leg. No need to treat unless the scales are bad.
pets question and answers,www.5d2d.com I've never had a red mite problem but you need to treat the hen house, the red mites live in cracks in the wood and come out at night to suck the hens' blood.
Lice powder for lice mite powder for mites and red mite have to treat the housing as well as can live off bird for to long and can reinfect birds
this link is for chickens as you do not say what birds its for.
