The Papilio cresphontes, commonly known as the giant swallowtail, is the largest butterfly in North America. The giant swallowtail is widespread across the United States, from southern New England to southern Canada, and southward to Florida and the Caribbean. They are particularly common in the southeastern regions, including Florida.
I find giant swallowtail butterflies incredibly fascinating due to their diverse adaptations to their environment and their unique defense mechanisms at each stage of their lifecycle.
Egg
Females lay eggs on the tops of the leaves of one of their preferred host plants. This is because the first larval instars are unable to move from plant to plant, so the mother must select an appropriate plant to support them. One egg is lain at a time, as opposed to in clutches.
Caterpillar
The larvae, known as “orange dogs,” have a unique defense mechanism. They resemble bird droppings, which helps them avoid predators.
When threatened, the caterpillars can extend a forked, orange-red gland called an osmeterium from behind their heads. This gland emits a foul-smelling chemical to deter predators.
Chrysalis
The chrysalis is mottled brown and green, resembling a twig or leaf to blend in with its surroundings. The giant swallowtail can only overwinter in warmer climates, such as Florida and the deep South, so in colder regions their pupae will enter a state of diapause to survive the freezing winter temperatures.
Adult
Adult giant swallowtails have a distinctive, erratic flight pattern. They often glide and flap their wings in a slow, deliberate manner, which can make them appear larger and more intimidating to potential predators.
Male giant swallowtails sometimes engage in puddling, where they gather on moist ground to extract minerals and salts, which are essential for reproduction.
The female swallowtails use a large variety of host plants to sustain their growing population. They use their antennae to detect the scent of the plants, and then use their feet to determine if it is a correct plant to lay their eggs.
Females use a variety of trees and plants to lay their eggs, including Orange (Citrus sinensis), Wild Lime (Zanthoxylum fagara), Hoptree (Ptelea trifoliata), Hercules Club (Zanthoxylum clava-herculis), Common Rue (Ruta graveolens), and Torchwood (Amyris elemifera ).
The giant swallowtail’s ability to adapt to different habitat and climates allows it to flourish across a wide area. Recently, its range has expanded northward, a change attributed to rising temperatures and absence of September frosts in these new regions. This has enabled larvae to survive before pupating. The immediate effects of this warming, as well as their effect on host plants, can explain the giant swallowtail’s range expansion. (Finkbeiner, Susan D.; Reed, Robert D.; Dirig, Robert; Losey, John E. (2011-07-01). “The Role of Environmental Factors in the Northeastern Range Expansion of Papilio cresphontes Cramer (Papilionidae)”. Journal of the Lepidopterists’ Society. 65 (2): 119–125.