The Eastern Tiger Swallowtail (Papilio glaucus) is a large and striking butterfly belonging to the order Lepidoptera and the family Papilionidae, which includes all swallowtails. Its genus Papilio is known for species that often display tail-like extensions on their hindwings, a feature thought to confuse predators. While not a plant, this butterfly is closely associated with various botanical hosts during its life cycle, making plant-insect relationships central to its ecological classification.
This butterfly is easily identified by its bright yellow wings with bold black tiger-like stripes, hence its common name. The wingspan ranges from 7.5 to 13.5 centimeters, making it one of the larger butterflies in eastern North America. Males are typically yellow with black striping, while females come in two forms: one that looks like the male, and another, known as the dark morph, which is almost entirely black. Both forms of the female display a distinctive band of blue spots on their hindwings.
Besides its primary name, the Eastern Tiger Swallowtail is occasionally referred to simply as the Tiger Swallowtail, though this can cause confusion with similar species in the western and central parts of the continent. In folklore and gardening communities, it may be called a “yellow swallowtail” or just “swallowtail butterfly”—names that hint at its coloration and tail-like hindwings.
Papilio glaucus is widely distributed throughout eastern North America, from the Great Plains to the Atlantic Coast, and from southern Canada to the Gulf Coast. It is a common sight in forests, woodland edges, meadows, gardens, parks, and riverbanks. Its adaptability to both natural and human-altered environments has helped it remain a common and stable species across its range.
Like many butterflies, Eastern Tiger Swallowtails face threats from birds, spiders, predatory insects, and parasitoid wasps. However, their large size and fast, erratic flight help them evade capture. The caterpillars, which resemble bird droppings in their early stages, later develop eye-like spots to deter predators. Despite these defenses, many larvae and pupae fall prey to natural enemies before reaching adulthood.
Adults live for about two weeks to a month, depending on weather and environmental conditions. They are typically diurnal, active during sunny, warm parts of the day. Multiple broods occur each year in the southern part of their range, while northern populations usually produce only one or two. Mating occurs shortly after emergence, and females lay eggs singly on the leaves of host plants.
The caterpillars feed on a variety of woody host plants, with favorites including tulip trees (Liriodendron tulipifera), wild cherry (Prunus serotina), ash, birch, and willow. These trees provide not just nourishment but also camouflage and protection during larval development. Once the larva is ready, it forms a green or brown chrysalis and enters the pupal stage, from which the adult will emerge.
Adult Eastern Tiger Swallowtails feed on nectar from a wide range of flowering plants, such as milkweed, thistles, phlox, joe-pye weed, and wild cherry blossoms. They are also known to sip moisture and minerals from mud puddles in a behavior known as puddling, especially common among males. This provides essential nutrients, particularly salts, that support reproduction and overall health.
Life Cycle of Eastern Tiger Swallowtail (Papilio glaucus)
The life cycle of the Eastern Tiger Swallowtail (Papilio glaucus) is a classic example of complete metamorphosis, consisting of four distinct stages: egg, larva (caterpillar), pupa (chrysalis), and adult butterfly. Each stage serves a unique purpose in the development of the butterfly and is shaped by seasonal and environmental factors.
The cycle begins when a female butterfly lays eggs singly on the leaves of suitable host plants, such as tulip trees, wild cherry, or ash. The eggs are small, round, and pale green to yellowish in color. This stage typically lasts 4 to 10 days, depending on temperature. The placement of the egg ensures the emerging larva has immediate access to food.
Once hatched, the larva enters the caterpillar stage, which lasts around 3 to 4 weeks. Early instars resemble bird droppings, a defense mechanism to deter predators. As the caterpillar grows and molts through several stages (instars), it becomes green with large false eye spots on its thorax, which help scare off birds and other threats. During this stage, the caterpillar feeds heavily on the leaves of its host plant to store energy for metamorphosis.
When the caterpillar is fully grown, it searches for a safe location to undergo transformation. It attaches itself to a surface using a silk girdle and forms a chrysalis, or pupa. The pupal stage lasts about 10 to 20 days, though in some cases—especially for the final generation of the year—it can overwinter in diapause, emerging the following spring. The chrysalis can be either green or brown, helping it blend into the surrounding vegetation or bark.
Eventually, the adult butterfly emerges from the chrysalis, a process known as eclosion. At first, the butterfly’s wings are soft and crumpled. Over the course of a few hours, it pumps fluid into its wings to expand them and waits for them to harden before taking its first flight. This marks the beginning of the final stage, during which the butterfly will feed, mate, and—if female—lay eggs to begin the next generation.
In warmer regions of its range, the Eastern Tiger Swallowtail may go through two to three generations per year, while in cooler northern areas, it typically completes only one or two generations annually. The speed of development is closely tied to temperature, day length, and food availability, which influence how quickly the butterfly moves from one stage to the next.
Each phase of the Eastern Tiger Swallowtail’s life cycle plays a vital role in its survival and reproductive success. From clever camouflage as a caterpillar to elegant flight as an adult, this butterfly demonstrates remarkable adaptations that have allowed it to thrive across a wide swath of eastern North America.