Chrysalis The green casing in which a caterpillar changes into a butterfly. Molt to shed its skin Instar A phase between two periods of molting in the development of an insect larva or other invertebrate animal. Scales A butterfly’s wing is made up of thousands of these. Camouflage The markings on an animal’s body that help it blend in with its surroundings. Proboscis The spiral, straw-like tube from which a butterfly is able to get nectar from flowers. Metamorphosis To change from a caterpillar to a butterfly Thorax The middle section of a butterfly’s body where the legs and wings are attached. Pupa an insect in its inactive immature form between larva and adult Larva an immature form of animals or insects that undergo some metamorphosis Head the front or upper part of the body of an animal Abdomen the segments of an insect's body behind the thorax. Migration to travel from one location to another Milkweed plant with milky juice that is the sole host plant for Monarch butterflies