Caterpillars eat like a group of teenage boys, consuming anything in their path, so expect caterpillars to consume entire leaves of their host plant. Don't worry about the plant and enjoy watching the caterpillar's single-minded devotion to eating. Eventually the very plump caterpillar spins a cocoon or chrysalis for its amazing transformation into an adult butterfly or moth. If you are lucky and observe carefully, you will be able to watch the new adult struggle out of its cocoon, expand and dry its wings, then take its first flight. Flying requires tremendous amounts of energy that the butterfly gets from flower nectar.
Butterflies prefer a varied diet and visit a number of different flowers.
Generally if you keep in mind a few general principles on flower shape, color, and fragrance, butterflies will come to your yard. Because butterflies have a mouth similar to a drinking straw, they prefer easy access to nectar. They do not hover, so they also need a landing area on a plant with sturdy stems. The flat center disc, with or without interior petals, is a perfect landing platform and dining area. Members of the Composite or aster family are ideal.