Serama and bantam polish both having issues. Serama was harder to get a picture of but is worse than the Polish.
If you suspect leg mites you cold coat the legs in vaseline or bag balm to try and choke them out. I would treat the birds themselves for mites as well. Look deep into their feathers near the shaft. If they do have mites I would spray or dust with permethrin or dust with sevin. Some people swear by DE, but I have never personally had luck with it.