Western Tiger Swallowtail (Papilio rutulus) is a large butterfly, with a wingspan of 2.75 to 4 inches. In our local area, it can be seen during all 12 months. However, numbers are negligible from November through February, and peak in June. Host plants include Cottonwood and Aspen (Populus), Willow (Salix), Wild Cherry (Prunus), Ash (Fraxinus), and Oak (Quercus).
It is a very active flyer, only rarely seen resting. So it is under-represented in photograph-based databases like iNaturalist.
Western Tiger Swallowtail is quite similar to Pale Swallowtail (Papilio eurymedon), but they can be distinguished by the difference in their color. Western Tiger Swallowtails are a deeper yellow. (Sometimes, of course, adjudicating the color can be a difficult judgment call, but there are also subtle differences in the pattern. It doesn’t help, though, that the two species can hybridize.)
It is found across western North America, from British Columbia to North Dakota in the north to Baja California and New Mexico in the south. It can be seen in urban parks and gardens, as well as rural woodlands and riparian areas.
