Black discolouration on birds feathers?

In my humble opinion, pet birds do not need to be sprayed for mites on a regular basis. These sprays do have chemicals in them that are not very good for your beloved pet when used too often. Unless you are using wood shavings or taking your bird outdoors, the chance of it getting mites is very slim. Perhaps it is a reaction to this spray. I would consult an avian vet regarding this situation,