This is an example of a female Eastern Tiger Swallowtail, Papilio glaucus. Like the Black Swallowtail, this species belongs to the Swallow tail family, Papilionidae. In this image you can see the iridescent blue stripe on the rear margin of the hindwing and a portion of the large orange spots. These are much less pronounced in the male. Additionally, the females of this species can also be found with wings that are all black where you see the large yellow bands on this specimen. You can visit the BAMONA website to see pictures of this form. The rear margins of their wings look the same, but the yellow has gone black elsewhere. The darker form of the female resembles the Pipevine Swallowtail and probably derives some protection from this resemblance.
This image is a slightly different angle on the same butterfly but it gives you an idea of their antenna shape and shows the coiled proboscis that they unroll to probe flowers for nectar. Eastern Tiger Swallowtails are strictly a US species. They are found in river and stream habitats bounded by deciduous forests. They range throughout the southern US and as far north as the Great Lakes. This specimen was photographed in Fort Worth, Texas which is on the western-most boundary of their range. I don’t expect I will see these large, beautiful butterflies out here in West Texas, but you never know.