Poisonous butterflies can be identified by bright colors or warning markings. For instance, the goliath birdwing from Indonesia has bright yellow and green wings. The color warns predators to stay away.
There are not many poisonous butterflies and none that are fatal to either humans or large mammals. The species that are toxic include the monarch, small postman butterfly, pipevine swallowtail and goliath birdwing. Bright black and orange wings characterize the monarch butterfly, a species that contains poison because of the food it eats. The monarch lays its eggs on toxic milkweed plants that the hatchlings feed on exclusively as caterpillars to become poisonous.
The pipevine swallowtail is another example of a poisonous butterfly identified by its distinctive coloring. Its wings are a metallic turquoise color with bold black and orange spots. Like the monarch butterfly, the pipevine swallowtail also gets its poison from the plant on which it feeds. The pipevine plant toxin builds up in the caterpillars to make them poisonous as adults. Birds tend to stay away from butterflies with this same coloring and pattern, so other species of swallowtail butterfly, such as the eastern tiger, spicebush and eastern black, have evolved to look similar to the pipevine.