My 18mo DD has been going through a fairly long biting stage. She goes to nursery and is in a room with 5 other children. There's one girl she bites in particular. It's so horrible to see, she races after her with her mouth open and the poor little girl cowers as DD approaches. 
DD is in other ways a really lovely little girl. She is quite chatty, open and smiley but seems to have these bouts of aggression. She also grabs at faces (which looks just as painful). She doesn't bite or grab at home.
Any tips on how to get through this?! The nursery staff are shadowing her and telling her it isn't nice and giving the other girl cuddles. She is currently the oldest in the room, I wonder whether she needs to hang out with older kids and get pushed about a bit?
Thanks in advance.