Why would a gardener be happy, overjoyed even, to discover an army of fat, black, spikey-looking caterpillars with red polka dots pillaging a prized ornamental vine? Answer: When the marauders are Pipevine Swallowtail butterfly larva and the vine is Dutchman’s Pipe (aristolochia macrophylla), one of their host plants.
For the ten summers and more since husband Gerald planted two pipe vines in the garden at Red Fox Cabin, we have kept watch on them.* We’ve admired the cute little Dutchman’s pipes they bear and checked the foliage for ragged holes that would give away the presence of larva. We’ve peered at black with blue swallowtails, hoping to spot the distinctive coloration of the Pipevine, inky black forewing and iridescent blue hindwing. However, sightings have been extremely rare and none have chosen to lay eggs on the beautiful Dutchman’s Pipe. Until this July.
Last Saturday evening as I was walking my Jack Russel, Lefty, or rather as he was leading me where he wanted to go, he tugged me toward the rear of the log cabin, where one of the pipe vines grows luxuriantly on a porch pillar. Lefty was intent on the rabbit or cat or whatever that he scented underneath the porch, but I was halted in my tracks by the sight of that vine, no longer luxuriant, but ragged, nearly defoliated, and crawling with the aforementioned fat black caterpillars–at least twenty. Thrilled by the sight and the realization that our vine had finally been discovered by a passing Pipevine Swallowtail, I rushed home with a disappointed Lefty to grab my camera and my Peterson’s field guide to caterpillars, for confirmation.
According to the guide, predators avoid Pipevine Swallowtail caterpillars because the vine that feeds them is toxic and makes them unpalatable. Also, when they are ready to pupate they tend to crawl away from their host plant and find other places to attach a greenish chrysalis with a silken thread. So, the total disappearance of the caterpillars two days later was not as alarming as it might have been. Photos and a ravaged vine prove they were there. Quite likely, somewhere on the Quarry Farm later this summer, a Pipevine Swallowtail, or maybe twenty, will emerge from its chrysalis and sail into the butterfly garden to dine, and with luck someone will be there with a camera. A photo of the shimmering beauty will be a fitting tribute to Gerald, who inspired us with his love of butterflies and planted the Dutchman’s Pipe so many years ago.
*[Pipe vines are native in some parts of the Northeast but not in Putnam Co., Ohio; ornamental pipe vines were common in Victorian gardens but are less so today. Pipevine Swallowtails can complete their life cycle only if they happen to find a host pipe vine or a Virginia Snakeroot growing wild or deliberately planted. Adults might stop to nectar in a flower garden but will move on if a host plant is not available.]