Has anyone had any problems with biting? My 4 year old bit his dads girlfriends son yesterday and really meant it. When asked why he said " I was trying to pull his ear off but it wouldn't come off"

To say I am stunned is an understatement. He's never done it before and has never as far as I know, been bitten himself.

I'd like to nip this on the bud before anything else happens and he draws blood

Try looking through this thread...I know it's for toddlers, but there may be some ideas you can use anyway. There are a couple of links you can try in there, as well.
I was going to merge the threads, but 4 is not a toddler, presumably there are other ways of dealing with it, too, as reason is starting to come into the picture more.

good luck!

http://www.sheffieldforum.co.uk/showthread.php?t=176130&highlight=biting