Tea tree oil definitely has the potential to kill mites on cats, but there is a big risk involved. First and foremost, tea tree oil can be extremely toxic to cats if ingested in large quantities. Secondly, Tea Tree oil can also irritate the skin, which could lead to worse symptoms such as inflammation and itching. If your cat is already prone to having flare-ups of skin issues, using tea tree oil as a Flea and Mite prevention strategy may not be the best idea.