this was supposed to be a black swallowtail butterfly
Location: southwest ohio
August 11, 2010 4:19 pm
i found a black swallowtail caterpillar,
(found that on your site) in my front yard. a few days later it put itself in a cacoon or chrysalis. yesterday i noticed something flying in the container but it was way to small to be my butterfly. WHAT IS THIS??????????
By all outward appearances, your Black Swallowtail had begun its metamorphosis into a chrysalis and things should have culminated in the emergence of a butterfly, but while it was still a caterpillar, your individual was parasitized by a type of wasp known as an Ichneumon. We quickly identified the adult Ichneumon that you photographed as Trogus pennator, which BugGuide indicates “is a parasitoid of swallowtail butterflies (Papilionidae), ovipositing in the caterpillars.“ The female Ichneumon lays a solitary egg inside the caterpillar using her stingerlike ovipositor. BugGuide has a nice series of images documenting this process. The Ichneumon Larva develops inside the the caterpillar, feeding upon its internal organs and allowing it to pupate into a chrysalis. At some point hidden from view, the Ichneumon Larva undergoes its own metamorphosis into a pupa, eventually emerging as an adult wasp and chewing its way out of the chrysalis through an irregular hole. The adult butterfly will not emerge once it has been parasitized. BugGuide also has a photo that illustrates that action. Back in the seventeenth century in Germany, artist and naturalist Maria Sibylla Merian became one of the first people to notice and document insect metamorphosis at a time when the accepted theory was spontaneous generation. Maria Sibylla Merian observed that caterpillars formed pupae and emerged as moths and butterflies as part of a natural process of metamorphosis, but she was puzzled that some caterpillars did not metamorphose in a typical manner, emerging instead as flies or wasps. She documented this puzzle in her intricate drawings which were published in a two volume book known as Caterpillars, Their Wondrous Transformation and Peculiar Nourishment from Flowers or simply The Caterpillar Book. You should be able to see the hole in the chrysalis. As a point of clarification, butterflies do not form a cocoon as their pupae are bare. A cocoon is usually spun of silk to cover a naked pupa. Most moths form a cocoon to protect the pupa.