[4] The eastern giant swallowtail caterpillars possess remarkable camouflage from predators by closely resembling bird droppings.

The species was historically considered to occur in the western United States and into South America,[4] but now those populations are treated as a separate species, the western giant swallowtail (Papilio rumiko), based largely on DNA evidence.

They also consume some exotic Rutaceae species that have been introduced to North America, such as gasplant, rue and sapote.

In specific local subpopulations (studied in Wisconsin, Ohio, and Florida), it was found that eastern giant swallowtail caterpillars do better on their local host plant than on other giant swallowtail host plants.

[5] Nectar plants for adults include Lantana, Azaleas, Bougainvilla, Saponaria officinalis, Hesperis matronalis, Solidago, Lonicera japonica, and Asclepias incarnata.

[4] They attach themselves to their substrate of choice and molt to reveal a brown, mottled chrysalis (resembling a bit of dead twig) in which they remain for approximately 10–12 days.

The caterpillars' intricate coloring patterns are an effective camouflage and defense against both vertebrate and invertebrate predators and parasites.

The osmeterium is an organ behind the head that “inflates” into an orange/red Y-shaped growth that resembles a snake's forked tongue.

By the fourth instar, the osmeterium is more than just a startle mechanism and also has bad-smelling and toxic mixture of acidic chemicals.

This last dependency is thought to be because the females, not the males, must identify the correct host plant for egg laying.

[9] Because of the butterfly's notably large wingspan (14 to 18 cm), eastern giant swallowtails are very strong fliers and are able to glide long distances with very few wing beats.

[4] Sometimes referred to as "orange dogs", "orange pups", or "bird poop caterpillars"[10] by farmers, the larva targets all varieties of citrus plants, often causing significant damage to new foliage and younger trees, which they can more thoroughly defoliate.

Outside of farms, the species is valued for its aesthetic appeal and can also be raised to butterflies successfully at home.

[4] Methionine, an essential amino acid in humans, has also been found to be an effective killer of caterpillars, with possible use as a nontoxic pesticide against eastern giant swallowtail larvae.