The Pipevine Swallowtail or Blue Swallowtail (Battus philenor) is a swallowtail butterfly found in North America and Central America. The butterflies are black with iridescent blue hind wings. They are found in many different habitats, but are most commonly found in forests. ~ wikipedia.org
Pipevine Swallowtails on musk thistle photographed at Pedernales Falls State Park in Johnson City, TX.