The brilliant tiger swallowtail butterfly (Pterourus glaucus) was designated the official state butterfly of Delaware in 1999. Three butterflies were chosen by students of the Richardson Park Learning Center as possible state butterflies, and a vote that included students throughout the state elected the tiger swallowtail as Delaware's butterfly symbol.
The tiger swallowtail butterfly is indigenous to Delaware and can be seen in deciduous woods, along streams, rivers, wooded swamps, and in towns and cities throughout the state.
Female tiger swallowtails are often mostly black or brown (mimicking the poisonous pipevine swallowtail butterfly). However, females can also have yellow and black tiger stripes very similar to the males. Females lays their eggs on host plants that include yellow poplar, black willow, black cherry, American hornbeam, red maple, spicebush, American elm, and sassafras.
When the eggs first hatch, the young caterpillers resemble bird droppings (an effective camouflage from predators). As the caterpillars grow, they turn green with a large head and bright "eyespots" (not actually eyes, but another tactic to discourage attackers). Many predators eat tiger swallowtail caterpillars including birds, squirrels, raccoons, and shrews.
Adult tiger swallowtail butterflies drink nectar from flowers (including milkweed, thistles, Japanese honeysuckle, ironweed, and red clover). In this way butterflies help with plant pollination and many people plant flower gardens specifically to attract these beautiful insects.