The bright orange butterfly weed (Asclepias tuberosa) is one of the most beautiful plants flowering in my garden. As I backed out of the driveway yesterday, I spotted an orange butterfly, perfectly mimicking the orange of the flowers, sipping nectar. It flew off when I got out of the pickup in an attempt to identify it (monarch and viceroy butterflies are the two most likely candidates). Later, I saw a spicebush swallowtail feeding on the butterfly weed.
It pleases me to think that the many types of native perennials and shrubs I've planted (including spicebush) are providing food for caterpillars and nectar for butterflies. Monarch butterflies, for example, breed exclusively on milkweeds, of which butterfly weed is one.
Butterfly weed has another appealing attribute - it likes poor soil with no mulch, fertilizer, or need for supplemental water. I planted mine three years ago, never watered it after the first year, and it blooms beautifully.