Normally in mountain areas adults fly from June through July. In the lower latitudes and altitudes there may be up to three broods, while in the more northern extents of the range there may be only one. Habitat Woodlands near streams and rivers, wooded residential areas, canyons, parks, and sagelands and mesas with creeks. May be seen at higher elevations. Food Caterpillars feed upon cottonwood, willow, quaking aspen, alder, maple, sycamore, hoptree, plum and ash.
Adults feed on flower nectar from a wide variety of flowers.
This is the commonest swallowtail observed in the West. A person can attract these butterflies to a garden by planting zinnias, milkweeds, thistles, penstemons and other flowers. Certain species of wasps lay their eggs on a caterpillar as the caterpillar is spinning its last silk threads before it pupates. At this point the caterpillar is totally defenseless. The wasp's eggs will develop inside the caterpillar and feed upon it, killing the caterpillar.