Zebra Swallowtail Butterfly

What is zebra swallowtail butterfly?

The zebra swallowtail butterfly (Eurytides marcellus) is a species of butterfly in the family Papilionidae known for its distinctive wing pattern, which features longitudinal black bands against a greenish-white or white background.¹

These butterflies are native to eastern North America. They exhibit seasonal variation, with spring broods typically being smaller than those that emerge in the summer. Physically, the species has a forewing span of 6 to 9 cm (2.5 to 3.5 inches) and possesses long tails on the hindwings measuring 15 to 25 mm (0.6 to 1 inch). The larvae of this species feed primarily on the pawpaw plant. While historically classified under the genera Iphiclides, Graphium, and Papilio, it is noted for its close resemblance to the European scarce swallowtail (I. podalirius).²¹

Why is the pawpaw tree essential for this butterfly?

The pawpaw tree is essential to the zebra swallowtail butterfly because it serves as the primary food source for the species’ larvae.¹²

The relationship between the butterfly and the plant is a critical aspect of the insect’s life cycle, as the larvae rely exclusively on the pawpaw to obtain the necessary nutrients for development. Without this specific host plant, the butterfly would be unable to sustain its population, highlighting the importance of the pawpaw in the butterfly’s natural habitat in eastern North America.¹²

How do butterfly wings change with the seasons?

It is a common misconception that butterflies undergo seasonal color changes through molting or bleaching, as birds and mammals do. In butterflies, seasonal variation is typically a result of different generations emerging with distinct physical traits rather than an individual insect changing its own appearance over time.

For species like the zebra swallowtail butterfly, the variation is generational. Because there are several generations in a single year, the adult forms that emerge at different times of the season vary considerably in their markings and size. Specifically, spring broods of the zebra swallowtail are typically smaller than those that emerge during the summer months.³

Unlike birds or mammals, which may shift their camouflage through seasonal molts regulated by light or temperature, butterflies do not replace their wing scales to adapt to changing backgrounds. Instead, their seasonal appearance is determined by the environmental conditions experienced during their development, leading to distinct phenotypes across the year’s broods.¹³

What are the stages of a butterfly’s life cycle?

Butterflies undergo a process called complete metamorphosis, which consists of four distinct stages in their life cycle:⁴⁵

• Egg: The cycle begins when an adult butterfly lays eggs, typically on a specific host plant that will serve as food for the emerging offspring.⁶⁵
• Larva (Caterpillar): Upon hatching, the larva focuses entirely on growth and development. It feeds voraciously, often on specific parts of host plants, and undergoes several molts as it increases in size.⁴⁶⁵
• Pupa (Chrysalis): The fully grown caterpillar enters this resting stage, during which it undergoes a dramatic transformation. Inside the protective chrysalis, larval tissues are broken down and reorganized into adult structures, such as wings.⁷⁸⁴
• Adult (Imago): The mature butterfly emerges from the pupal case. After spending time drying its wings, the adult is capable of flight and reproduction, shifting its focus from the growth-oriented habits of the larva to mating and nectar feeding.⁴⁶⁵