The Pale Swallowtail is the only whitish (off-white to rich oucre) and black swallowtail in the west and flies mainly in late spring and early summer in most areas. You can find them from sea level to timberline in deciduous and deciduous-coniferous woodlands and edges, including suburban areas. Jeffrey Glassberg, author of Butterflies through Binoculars: The West, refers to them as “avid mudpuddlers.” So, keep your eyes peeled for them sipping up nutrients from moist substances like mud. Males are tireless in their effort to find a mate, patrolling hillsides, canyons, and mountain summits for females. Caterpillars feed on buckthorn, coffeeberry, alder wild plum, birches, aspens, and others.
Photo by: Glenn Marangelo on 7/16/21 near Philipsburg, MT