Keep an eye on the others (see if the bad habit has spread - kind of like egg eaters spoiling the flock). If it is just the one girl you'll need to keep her seperated until the others have healed (don't know about successful reintegration, either).
If it is impossible to seperate: Try the pine tar, she'll get tired of that very fast.
Good luck, glad you're making some headway in identifying the problem!
If it is impossible to seperate: Try the pine tar, she'll get tired of that very fast.
Good luck, glad you're making some headway in identifying the problem!