Eastern Tiger Swallowtail, females uses mimicry to protect themselves.

The male tiger swallowtail (Papilio glaucus) is yellow with four black "tiger stripes" on each fore wing. Females may be either yellow or black. The yellow morph is similar to the male, but with a band of blue sapphire spots along the wing, while the dark morph is almost completely black.

Sadly for the adult tiger swollowtail it's a tasty meal. Happily the females uses mimicry to protect themselves from predators by pretending to be the poisonous pipevine (philenor). The dark females are more common in areas where the pipevine is found.