Invertebrates
Giant Swallowtail
Papilio cresphontes · also called giant swallowtails, orange dog
A giant swallowtail glides between citrus trees on wings broader than any other butterfly in North America, while somewhere below, a caterpillar disguised convincingly as a bird dropping waits motionless on a leaf, ready to flash a foul-smelling orange gland at anything that gets too curious.
Overview
The giant swallowtail, Papilio cresphontes, is the largest butterfly species found in North America, native to forested and citrus-growing habitat across a broad range of the eastern and southern United States extending into Mexico and Central America. Its record-setting size, bird-dropping-mimicking caterpillar, and foul-smelling defensive gland make it one of the more remarkable and agriculturally notable butterflies on the continent.
A caterpillar with two very different disguises
Rather than relying on a single defence, the giant swallowtail caterpillar combines passive camouflage as an unappetizing bird dropping with an active chemical deterrent, a forked, foul-smelling gland deployed only when the disguise alone fails to work.
Status
Least Concern — widespread and common across suitable forested and citrus-growing habitat throughout the eastern and southern United States.
Giant Swallowtail: common questions
Why is the giant swallowtail caterpillar called the orange dog?
This species' caterpillar feeds readily on citrus trees and can cause noticeable damage to young plants, and citrus growers have long used the nickname orange dog to refer to it, a name that has stuck in agricultural circles even though the caterpillar itself is more closely associated with camouflage and defence than with actually resembling a dog.
How does the giant swallowtail caterpillar avoid predators?
This species' caterpillar relies on two main defences, a mottled brown and white pattern that closely resembles bird droppings, providing effective camouflage against casual predators, and a forked, fleshy orange gland called an osmeterium that it extends from behind its head and uses to release a foul odour when directly threatened.
How big is the giant swallowtail compared with other North American butterflies?
This species holds the distinction of being the largest butterfly found anywhere in North America, with a wingspan that exceeds that of every other native butterfly species on the continent, making it one of the more immediately impressive butterflies to encounter in the wild.
Is the giant swallowtail harmful to citrus trees?
Its caterpillar can cause noticeable feeding damage to young citrus trees, particularly in nurseries or small plantings, which is why it earned the agricultural nickname orange dog, though on mature, healthy citrus trees the damage is generally limited and rarely threatens the tree's overall survival.