Migrating butterflies, such as the monarch en route from Central America to the United States, scout a wide area for the most attractive stopovers. Color plays a significant role in their selection because color provides a clue to nectar-rich flowers that meet the energy needs for flight. Color, however, can fool butterflies. Petunias and geraniums, for example, provide good color but are poor sources of nectar. Cosmos, verbena and zinnia are good sources of both color and nectar.
Butterflies require different foods in the caterpillar stage of their lives.
The beautiful adult butterflies and moths flitting through the gardens are looking not only for a meal for themselves but for a place to park their offspring. Providing for caterpillar needs is really the well-kept little secret of butterfly gardening. Caterpillars can't fly around in search of gourmet delights, so Mom must plant the eggs on a suitable buffet. But the gardener who wants butterflies should be prepared to share some of the bounty with caterpillars. After the caterpillars eat their fill, they pupate into an adult.