They have an osmeterium, an orange, y-shaped gland on their neck which gives off a strong, unpleasant odor when the caterpillar is threatened. Many swallowtails have an osmeterium, including the Zebra Swallowtail . Butterflies Butterflies are fragile and almost defenseless creatures. They rely on a variety of strategies to protect them from hungry predators. The Goliath Birdwing is a poisonous butterfly from Indonesia.
Some butterflies are poisonous.
When a predator, like a bird, eats one of these butterflies it becomes sick, vomits violently, and quickly learns not to eat this type of butterfly. Batesian mimicry is when a non-poisonous species has markings similar to a poisonous species and gains protection from this similarity. Since many predators have become sick from eating the poisonous butterfly, they will avoid any similar looking animals in the future, and the mimic is protected. An example is the Viceroy which mimics the poisonous Monarch butterfly . Tropical Queens Monarch butterflies are two poisonous butterflies that have similar markings.