Euploea; Print; Euploea is a genus of milkweed butterflies. The species are generally dark in coloration; often quite blackish; for which reason they are commonly called crows. As usual for their subfamily; they are poisonous due to feeding on milkweeds and other toxic plants as caterpillars. The latter are aposematically colored to warn off predators from eating them; and the adult butterflies are often mimicked by unrelated species which are not or less poisonous.