I know it won't be popular, but it works.
Bite her back. IF you see her bite, then immediately say NO biting and bite her back. Just enough to make her eyes wide. Then tell her "See it hurts." Don't hurt people!!!!
Give the daycare worker permission to separate her from the other kids for the entire day if she continues to bite. Tell the daycare worker to remind her repeatedly while she's in time-out that she bit someone and it hurt them so she can't play with the other kids. If you hurt the other kids, you can't play with them.
Some would say that you should only do time-out for one minute per year of age, but that is hogwash. A two year old in a two minute time-out is a joke. They could care less about a two minute time-out. If it isn't painful (meaning they cry), then it wasn't a punishment.
Sometimes we have to be really harsh with our children to spare the kids they have to be around. I would rather be harsh with my child to protect the others than know that other children are being hurt and have to endure my child's wrath for any period of time.
My oldest bit me....I bit her back one time. She never did it again.
My second child bit the little girl I watch. I bit her back and spanked her bottom because she lied to me about it...though I could see the dark red teeth marks on the little girl's hand. She has never bit again.
My cousin had a problem with biting. He was about to get thrown out of daycare (they would do that back in those days). We were visiting and he bit my brother in the back so hard that he drew blood. My aunt was horrified. Not only was she able to see the damage he would inflict for herself (instead of being told by a daycare worker)...but it was a relatives son.....so she bit him back. She bit his arm hard enough to make his eyes open wide and leave a slight red mark. He cried like she killed him. Then she kept making him look at my brothers back and saying you hurt your cousin. Look he's crying and he's bleeding. Look what you did...see it hurts to bite. DO NOT BITE!!!!
She told my mother later that he never bit another child again.
PS It irritates me to no end that people will tell you to just ignore it or separate her when she does it because it is a phase. My girls had to endure a cousin constantly being aggressive and hateful to them for over two years. He got so bold (because his parents figured it was just a phase...and would separate him for a few minutes) that he stepped on my infant daughters head and stood on her...He knew what he was doing because he was looking to see if anyone was watching. I also caught him looking around one day while they were playing and then he proceeded to whack my daughter in the head with a toy.
No child should have to endure being bit, hit, scratched, or bullied!!!!! It is the society that we live in that we care more about the offender than the victems. If you deal with it immediately in a way that they can understand...they won't do it again. If a child gets burned by a flame, they won't stick their hand in it again. They do understand. (and no I'm not advocating that you burn your child....it is just a point to prove that kids can learn and understand even at a young age)
Does she look to see if you are watching when she's going to do something you have told her not to do????? Does she pull her hand away if you say no???? Are there things she doesn't do anymore because you have told her no????? Then she understands.
Sometimes we have to think about others. The other kids should not have to endure your child's biting. Those parents that say to ignore it, that it will pass probably have never had their child abused.
I am very passionate about this because I have two sweet girls...I immediately dealt with their normal behavior issues like biting. They never did again. They hit me once. They bit once. They didn't throw tantrums for very long at all. WHY????? Because I dealt with it immediately. I understand that my children are intelligent. If I can train a puppy to go on a paper in a few days....then I can teach a two year old not to bite. Sometimes you have to be a little harsh. Not abusive. There is a difference. And ALWAYS back up discipline with love, hugs, and kisses.
If I get a ticket for speeding, I'm not mad at the police officer for giving me a ticket. I was doing something wrong. My children know I love them. They love me. They are sweet, loving, caring little girls. They have not been traumatized because I disciplined them. But they did learn quickly. And no one had to endure them for more than once.
Let me stop. I hope you can find a way to deal with a very normal behavior quickly. It is a phase. And it can be handled with quickly so no one else has to be hurt.