The Eastern Tiger Swallowtail butterfly is easy to identify due to its large size and their bright yellow color, with black tiger stripes and patterns along their wings.  The male has a few soft blue and brighter orange spots at the rear of its hind wings near their tails.  The female can be found in not only the light form, (similar to the male, except she has many more blue highlights along her wings), but she also can be found in the dark form, (which also exhibits the blue pattern and some orange and yellow spots), and otherwise is a soft black color overall.  The female dark form mimics another species called the Pipevine Swallowtail.  It is generally believed that if an area has an abundance of Pipevine Swallowtails, then there will be more dark forms of the female Eastern Tiger Swallowtail.  Since the Pipevine Swallowtails eat from a plant called the Pipevine, they tend to be considered not so tasty to predators; hence, the female dark form Eastern Tiger Swallowtail tends to not be bothered by predation.