Giant Swallowtail

The Giant Swallowtail (Papilio cresphontes) is a wonderful example of the obvious naming conventions among lepidopterans as it has swallow-tails and indeed is gigantic. With a wingspan of as much as 5.5 inches, this is one of the largest butterflies in Florida and in fact the entire United States. They are also an excellent example of countershading, as they are dark when seen from the top, but a bright yellow from beneath. This makes them easy to differentiate from other swallowtails, who often do not display such obvious color differences on top and bottom.

Giant Swallowtails start life as a tiny, spherical yellow or orange egg laid on the newest and freshest growth of their host plants, which include members of the citrus family as well as Common Rue (Ruta graevolens).

From that tiny egg emerges a caterpillars that is equal parts remarkable and unusual. The caterpillars do all their best to look shiny, wet, mottled and well, a whole lot like bird poop. In the world of insects there are a few ways to avoid being eaten: don’t be seen at all, be toxic, look like something toxic, look big, or look like something your predator already ate and discarded. It seems that birds are perfectly disinterested in further study of something they have already gotten rid of.

The caterpillars also have a backup defense mechanism called osmeterium. The osmeterium is a fleshy organ where caterpillars of swallowtail species sequester essential oils from their host plants, also known as terpenes. These oils coat the normally hidden osmeterium which can be everted or pushed out when the caterpillar is threatened, giving off a very foul odor. Giant Swallowtails have bright red osmeterium, which can extend nearly half an inch from the head of a large caterpillar.

Giant Swallowtails have terrific camouflage while in chrysalis too. They usually pupate along the side of a twig or small branch, and their pupa looks almost exactly like tree bark. The edges of the chrysalis are even ragged to look like a broken twig.

Giant Swallowtails prefer warmer weather, and fly in Central Florida from late spring through early fall. They are common in areas where citrus groves proliferate, and can cause some defoliation of trees, though rarely enough to cause a real problem for citrus farmers (who call them "Orange Dogs"). They also have a variety of native host plants, including Wild Lime (Zanthoxylum fagara) and Hercules Club (Zanthoxylum clava-herculis), and seem to actually prefer these to non-native cultivated citrus.