Cat biting self

Question
when scratching my cats back by the tip of the tail he bites himself on the left front paw. do you have any idea why or what should I do about it?

Answer
Pamela,

Yes, I have seen other cats and even dogs exhibit similar behaviors.  Unless, your cat is injuring itself when it bites the left front paw (which I doubt), I would not worry about it.  

As to why the cat exhibits this behavior I can guess it is like a nervous tic, but, this just a guess.

Best regards... Norm.