It's not "officially" spring until we see--and photograph--the spectacular Western tiger swallowtail, Papilio rutulus.
That's what I posted April 2, 2021 on Bug Squad after seeing one land March 30 on a white lilac bush in a Vacaville park. It lingered long enough for a few photos and then fluttered away.
This butterfly's wings are a brilliant yellow with black stripes. Blue and orange spots accent the "tails" on its hindwings.
Fast forward to today: The Entomological Society of America (ESA) has before its members, a proposal to add the common name, "Western Tiger Swallowtail,” to the scientific name, Papilio rutulus.
Most of us have not called it anything else. Oh, wait, there was "That Big Yellow Gorgeous Butterfly" and "Ol' Yeller" and "Sunshine Butterfly."
The ESA-approved name, if the members agree, would be "Western tiger swallowtail." Yes!
Presently there are 10 species within the family Papilionidae that have common names established by ESA. None describe species that are primarily found west of the Mississippi.
"Western" reflects its broad distribution over the western United States, as ESA says. "It is the most abundant of the 'tiger swallowtails' in this part of the U.S., paralleling the distribution of Papilio glaucus (tiger swallowtail/'eastern tiger swallowtail') which is the most abundant species in the eastern United States."
Also up for discussion and approval are these proposals for common names:
- "Two-tailed swallowtail" for Papilio multicaudata
- "Eastern tiger swallowtail" for Papilio glaucus
- "Pale swallowtail" for Papilio eurymedon
See the ESA database of common names, which includes more than 2,000 common names of insects and is searchable by common name, scientific name, author, order, family, genus, and species.
Butterfly guru Art Shapiro, UC Davis distinguished professor of evolution and ecology who maintains a research site, Art's Butterfly World," monitoring the butterfly populations in Central California since 1972, has always called Papilio rutulus by the common name of Western tiger swallowtail. But mostly he calls it Papilio rutulus. He writes on his website:
"The Western Tiger Swallowtail is basically a species of riparian forest, where it glides majestically back and forth along the watercourse. It has expanded into older urban neighborhoods where several of its host genera are grown as shade trees, and behaves as if the street were a watercourse. In the high country and on the Sierran east slope its usual host is Aspen."
"One brood (June-July) at higher elevations; one and a partial second at Washington; 2-3 at lower elevations with a long flight season (late February or March-September or October). An avid puddler. Visits Yerba Santa, California Buckeye, Milkweed, Dogbane, Lilies, Coyotemint, etc., etc. and in gardens frequent at Lilac and Buddleia. Spring individuals are smaller and usually paler than summer. Low-elevation hosts include Sycamore (Platanus), Ash (Fraxinus), Cherry and other stone fruits (Prunus), Willow (Salix), Privet (Ligustrum), Lilac (Syringa) and (in Sacramento County) Sweet Gum (Liquidambar)."
Have you seen any Papilio rutulus this year? Or the Western tiger swallowtail? Or "That Big Yellow Gorgeous Butterfly?"
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