[matese]

Sounds like play biting to me. As others have suggested, yelp or say ouch, follow up with a firm no biting command, that's the command I use, what ever command word you use for no biting must be consistent, use the same word, you and all family must use the same command words. He is still a baby at 6 months, yorkies are very smart, but stubborn at times. My boy is 4 y/o and pretty much trained, when he does do something he's not supposed to do, and I tell him NO, he'll get in my face and bark at me, he hates the word NO and will argue with me, all the while I keep telling him in a soft but firm voice NOOOOOO. For treats make him sit and stay and say easy before you hand over the treat.If he snaps at the treat pull your hand back or cup your hand over the treat, do not give the treat, reward only when he obeys your command words If you have not taught him the sit, down, stay and come command, I would start working on that now. They are the basic commands. If there is a toddler or young child in the house, supervise closely, baby or young child waving hands and arms around may cause puppy to think it's an invitation to play. Teach the child or baby to be gentle when petting or handling the dog. Most Yorkies are fast learners, when they do something right treat and lots of praise, happy dance also helps, they love to please their owners, treat and lots of praise.