I hope I never have to deal with scaly leg mites, but if I do, I will follow this advise:
Here is a copy of threehorses' excellent advice to another:
copied from this thread: http://www.backyardchickens.com/forum/viewtopic.php?pid=2740856
=First, soak the bird's legs in a solution of warm water with some epsom salts in it to soften the scales. Mites are actually burrowed into the skin of the leg and are causing irritation and build up of stuff which is raising the scales and irritating the skin. The soaking softens up the stuff. You then use a toothbrush to scrub at the legs to remove whatever build up you can. Pat the legs dry.
Then you can either use ivomec 1% injectable topically on the legs, or you can use pour-on ivermectin 5% cattle wormer on the bird - IF - your birds have been wormed within 6 months with a broad spectrum wormer.
Personally, I'd recommend the scrub, worm your flock with wazine 17 (piperazine 17) in the water, and use olive oil on the legs or VetRx daily for 2 weeks then worm them with the pour-on ivermectin (generic, 250ml bottles are the most affordable option). Worming all the flock with ivermectin will kill external parasites as it's likely other birds in the flock have mites but not signs of it yet on the legs. But you have more than one option there.
Here is another good thread, and an exerpt from it: http://www.backyardchickens.com/forum/viewtopic.php?pid=2713525
I have never done any worming is this somthing i need to do regulary ?
and as far as the dusting Is it Just powder you put on the bird?
Thank you all for everyones help with my questions. I also have seen a little bit of that legg stuff on another bird in that flock. ...........
On the worming, yes - it is good to do. They can technically live with some worms, but it causes a constant state of slight inflammation where the worms are, they make scars in the digestive tract if they burrow, and they steal their food - so they lower their immunity. I just worm twice a year with something broad-spectrum. For an unwormed flock, just worm with Wazine 17 (piperazine 17) first. Then go back and worm with something like fenbendazole (safeGuard for horses or goats), pour-on cattle ivermectin, albendazole (Valbazen), levamisole, etc. One of those will do the trick as the second worming.
How many do you have with this bird? Soak the legs of at least the two effected birds in warm water with some very gentle soap VERY dilute in it (ivory, or better yet - something like Nolvasan antiseptic diluted to a capful per a quarter of water. Scrub the legs with a toothbrush to get rid of the excess scaliness. The scaliness is made both by the gunk coming from mites that are burrowing under the skin (quite like mange mites do) as well as the products of irritation of the skin itself. Pat dry. Then you can use the 1% ivermectin on the legs. Dilute with a little water to get it to soak in. Or you can worm with ivermectin 5% cattle pour-on (PM me for the dosages) and you'll get the second worming done and be able to do it usually twice annually with ivermectin thereafter. ONLY use the 'broad spectrum' type wormers on birds over four months who have been wormed with wazine first.
I suspect the marks on the comb are also scaley mites which can and do migrate to combs as well, though they are more commonly found under the scales of the legs.
Still continue to give the vitamins, etc, as this will be good for their immunity.
Worm with Wazine.
Get started on working on the legs by soaking and scrubbing. (You can put olive oil on them after the cleansing). repeat the oil part daily until 2 weeks later.
Two weeks later:
Worm with ivermectin pour-on (birds over four months) which will kill the mites and the rest of the worms. (Reworm birds under four months with wazine two weeks from this date).
Continue oil for another week.
Note: Sometimes the scales will bleed after you kill the mites as they dislodge from the skin. Be forewarned. It is normal. That's just an indication of exactly how much damage they do under those scales where we can't see.
The scales might not return to normal, but at least the issue won't be there anymore.
On dusting, permethrin (the chemical you want - check the active ingredient on the label) usually comes in a handy shaker can. I find it handy but a little annoying. So I wear gloves, shake some into my hand, and then use my hand to put the powder on the birds - under their wings, under and around their vent, under their bellies, back of neck - use your gloved hand to ruffle the stuff in at each place as you apply it. Try to keep it out of their mouths and eyes. You'll get the feel of it. Repeat in 7 days.