Western Tiger Swallowtail (Papilio rutulus) lives in open woodland across Western North America. It feeds on willow and cottonwood.
Fascinating facts about the Western Tiger Swallowtail
- Newly hatched caterpillars look like bird droppings, a camouflage that hides them on leaves. As they grow they turn bright green and develop a pair of large yellow eyespots with black and blue pupils, making them conspicuous to predators. The eyespots, together with the green colour, signal that the larva is no longer a harmless droppings mimic.
- During summer, a pupa can transform into an adult in just 15 days after pupation, allowing a rapid emergence when conditions are warm. If pupation occurs in autumn, the butterfly remains dormant until the following spring, overwintering as a diapausing chrysalis. The length of the pupal stage is variable, lasting from a couple of weeks to several months depending on environmental conditions such as temperature and food availability.
- Male western tiger swallowtails are frequently seen gathering at pools, streams and rivers during the spring. They form loose congregations, often mixed with other swallowtail species, where they sip water and mud. While feeding they draw out essential minerals and moisture that support their active flight and reproductive efforts. This water-feeding behaviour is a regular part of their daily routine in both urban parks and natural riparian zones.
- Unlike many tropical swallowtails, this species can survive cold winters as a diapausing pupa beneath snow, likely using cryoprotectant chemicals. This adaptation lets it persist in boreal woodlands.
Sources
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At a glance
RangeWestern North America
HabitatOpen woodland
DietWillow and cottonwood
About the Western Tiger Swallowtail
As the Western Tiger Swallowtail dances through the sun-dappled forest, its iridescent wings beat in a hypnotic rhythm, casting a shimmering aura of yellow and black across the leafy underbrush. With each delicate flutter, the butterfly navigates a world of subtle scents and shifting light, its compound eyes drinking in the vibrant hues of blooming wildflowers as it sips nectar from the sweetest blossoms. In its effortless glide, the Western Tiger Swallowtail embodies the very essence of aerial elegance, a living embodiment of the wild beauty that surrounds it.
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