A dab of bird dropping rests on a leaf. It must have landed there when a bird passed over. But wait! It’s moving. It’s not a dropping after all. It is a tiny caterpillar, its coloration acting as a camouflage against predators.


This young caterpillar (larva) can stay in plain view since it looks like a distasteful bird dropping that creatures would not want to eat. It’s brownish-black with a light-colored saddle pattern on its back. The saddle pattern is another camouflage technique. It confuses a predator by making it harder to tell exactly what shape the caterpillar is.


This caterpillar is in its first stage (instar) of development. It will go through five instars, getting bigger with each one, until it’s about 2 inches (5 cm) long. Because it can be a pest in citrus orchards as it gorges on the foliage, it is known as orange dog or orange puppy.


By the time the larva has reached its fourth stage, it can use another defense technique against predators such as wasps, spiders, ants, or flies. This time a spider threatens, approaching the larva, ready to attack. But the caterpillar is ready. Behind its head is an organ that can “inflate” into a V-shaped red-orange growth that resembles a snake’s forked tongue. It is filled with harmful acidic chemicals that are toxic to any small predator. Now the larva touches the spider with its red-orange “tongue.” The spider jerks away.


When the larva has reached its fifth stage of development, it is ready to pupate. It searches for a sturdy, vertical plant or man-made object such as a fence, attaches itself to it, and forms a brown chrysalis.

Tropical swallowtail caterpillar (Papilio cresphontes) with orange horn-like, V-shaped osmeterium (scent organ), Amazon rainforest, Peru


Over the next ten to twelve days, changes are happening. And then one day, out of the chrysalis emerges a beautiful yellow and black butterfly. It’s big! It’s the largest butterfly in North America, the giant swallowtail butterfly.


With a wingspan of 5½ to 7 inches (14-18 cm), it’s a strong flier, able to glide long distances between wing beats. It drinks nectar from many different flowers and even sips liquid from manure. It lives in forests and citrus orchards and is a common visitor across the United States.
Perhaps a common visitor, but nothing is common about this beautiful, exceptionally large butterfly. Sighting one is a special event!