That's what UC Davis distinguished professor Art Shapiro called out when he spotted a pipevine swallowtail foraging on wild radish as we trudged up Gates Canyon Road several years ago.
It's a beautiful butterfly, and one of the first we see in the spring. It's also called a "blue swallowtail," in reference to its iridescent-blue hindwings.
Our first sighting this year occurred April 30 in the Ecological Garden of the UC Davis Student Farm. We photographed the butterfly foraging on Jupiter's Beard, Centranthus ruber.
"The signature riparian butterfly of our region, occurring along streams in foothill canyons and on the Central Valley floor, essentially everywhere where its only host plant, California Pipevine or Dutchman's Pipe, Aristolochia californica, occurs," Shapiro writes on his website, Art's Butterfly World.
"It is unmistakable and very conspicuous as both a larva and an adult. Only the pupa is cryptic (either brown or green, with a delicate golden filigree)."
Shapiro, a UC Davis Department of Evolution and Ecology faculty member who has been monitoring butterfly populations of Central California since 1972, says that "this species is warningly colored and inedible to vertebrate predators. It derives its protection from the toxic aristolochic acids produced by the host, which it sequesters; females even pass these along to the eggs, which are also protected (and are brick red, laid in bunches of up to 20, and quite conspicuous). Eggs are laid only on young, tender, growing shoot tips and the larvae must begin by feeding on these. Initially they feed in groups. As they get larger they scatter and can tackle large, mature leaves. But because these react to feeding damage by becoming more toxic and unpalatable, a larva will feed on a single leaf only for a short time and then has to move on. Eventually most or all leaves end up damaged, but few are badly damaged. The larvae also feed eagerly on the immature fruits, which look like small bananas with fluted edges. In big swallowtail years little if any seed ends up being set."
The butterfly "flies from late winter (February-March) to autumn (October, occasionally November) but is much more numerous before the 4th of July than later; typically it has two large flights followed by stragglers the rest of the season, often with a 'blip' upward in August. Usually the host plant stops growing in June, and thereafter there are no sites suitable for egg-laying--unless there is a local catastrophe (usually fire, though weed-whacking will do). Then the plants regenerate rapidly, producing new growth in the off-season, and any females around at the time quickly find and make use of the new shoots. Adults routinely live a month or so."
Shapiro also says that adults "are eager visitors to many flowers, including wild radish, California buckeye, blue dicks, Ithuriel's Spear, and Yerba Santa. In summer they regularly nectar at yellow starthistle when there are no native plants in bloom."
We remember admiring dozens of pipevine swallowtails in the nine-acre Hallberg Butterfy Gardens, a wildlife sanctuary in Sebastopol, West Sonoma County, and visiting with Louise Hallberg (1917-2017)). She kept meticulous records and thoroughly enjoyed showing visitors around. We posted a Bug Squad blog about her and her garden in 2015 and captured an image of her on her front porch.
How did this butterfly get its name, Battus philenor? According to Wikipedia, Battus refers to the founder of the Greek colony of Cyrenaica, Battus I, and philenor is derived from the Greek word meaning "fond of husband."
Who knew?