When the Monarch becomes a butterfly, it no longer eats milkweed, but it still has the chemical in its body. The butterfly shows that they are not good to eat with their bright orange and black wings. This is warning coloration. A bird may try to eat a Monarch, but it will become sick and vomit after eating it. After this experience, the bird learns not to eat another Monarch, and also any other butterfly which is similar in appearance.