hair loss on the ears

hi, About a week ago I noticed a tiny bald patch on each side of my cat's ears. Yesterday I checked again and I believe the patches got bigger and she now also has a wound on one ear which I'm guessing is from scratching too much. I checked the other 2 cats and 1 other cat seems to have less hair on the outer edge of each ear as well but I'm not sure if that was always like that or not. I would like to know if I should go to the vets with this or if there are home remedies I could use or if I should just keep an eye on it.  

Hello!  The trouble with talking about cases in this way over the internet, is that while I can see the symptom well enough, I cannot do the tests or see enough context to safely or ethically diagnose the problem - and even if I could, I cannot see any of the safety issues that might be involved in treatment.  This service is not intended to save a visit to the vets and only your own vet (plus or minus emergency folk or referral specialists) is allowed to diagnose and prescribe for your cat.   In this case, Ringworm may be an issue;  Demodex may be possible, if less likely; endocrine, autoimmune issues, skin cancers as well as itchy mites might also make the differentials list.  Your vet will add more or disregard some of these ideas when they can see the full patient.  Giving an appropriate remedy for the cause is important, so depending what they think it is, the treatment will be different.  Furthermore, some of the differentials (ringworm, some mites) may be transmitted to humans and if this is the case, your vet will want to talk this over with you.  Some of the possibilities may be more likely in cats with underlying problems, and they might also want to check that theres nothing else going on. So in conclusion, yes - this change is potentially worth a visit to the vets.  Please do let us know what they find.