‘Biter’ is a slang word for a cheat or swindler, e.g. a card-shaper. When he
himself is cheated by his prospective victim, ‘the biter is bit’. In a general
way, this refers to any form of retribution. As Laertes says in Shakespeare’s
_Hamlet_ after being wounded by the rapier that he himself has poisoned, ‘I am
justly kill’d with my own treachery.’