The normal yellow male is shown on top with the BLACK FEMALE FORM shown below. This is a rare anomaly that happens randomly and is a result of genetic variation in the TIger swallowtail, what is happening is that evolution is helping the females mimic the poisonous Pipevine Swallowtail (Papilio troilus) which predators know is inedible. It's like watching evolution in action! If you have a normal female you must add this to your collection, such a conversation piece!