The Passion vine butterfly is beautiful with its orange and black markings. It is similar to the monarch and is one of several migratory butterflies. Its range extends from Argentina through Central America, Mexico, the West Indies and Hawai`i to the southern United States, and as far north as the San Francisco Bay Area on the West Coast. It is occasionally found further north. Its wingspan is 2.75 to 3.75"
The larvae are a combination of black, orange and white, depending on their stage, with conspicuous black spines. They are poisonous if eaten. If you see this butterfly, there must be a passion flower vine (Passiflora sp.) growing nearby. The caterpillar feeds exclusively on passion vines. They often occur in large numbers and can quickly defoliate a young or newly planted vine. Control measures may be needed. Once the plant becomes a large vine with many leaves, their feeding will generally not produce significant damage. In addition, this pest often becomes highly parasitized (under good biological control).
If you decide to spray, BT (Bacillus thuringiensis;Dipel) would be a good selection. Even though the adults feed on the nectar of several different plants, they only lay their eggs on passion flower vines. Tall verbena (Verbena bonariensis), pentas (Pentas lanceolata), and lantana (Lantana camara) are all favorite nectar sources of the butterflies.