Ear mites is something that cats make quite often. It localizes inside the ears and you know a cat has mites when you see inside the ears some black dirtiness. The good news is the treatment is not difficult, there are many kind of treatments for this.
I have now a few cats in my foster that have ear mites and I treat the with some special ear drops for this.
The first sign of ear mites is when the cat scratches her ears often. If you suspect you cat might have ear mites take her at the vet for a check and if it will be confirmed you will receive the proper treatment.