My winter white hamster

Question
I have a winter white hamster. He had never bitten me before, until now.I have no other hamsters, and I always wash my hands before I put my  hand in his cage. He bites me almost every time that I put my hand in or near his cage. He does this even when I don't touch him at all. Why is he doing this? Is there any way to stop this?

Answer
He has become territorial
This is not unusual for hamsters. Especially if he is fully mature.
I suggest you get some thin garden gloves to pick him up with. This way he can bite you all he likes but wont get anywhere and should hopefully be able to reduce the habit. when he doesn't bite you give him a small treat like a bit of carrot