October 22, 2021
Black swallowtail caterpillars (Papilio poxyxenes) can be found in various settings such as gardens, fields, wetlands as well as many other areas. Most often everyone sees butterfly caterpillars in the spring. The black swallowtail caterpillars seen in the spring will emerge over the summer as black swallowtail butterflies.
Did you know that butterfly caterpillars overwinter? Usually caterpillars seen in the fall with the shorter days and cooler temps will overwinter. Overwintering black swallowtail caterpillars may be observed in the fall on a host plant.
Host Plants
Hosts plants are the plants butterfly caterpillars use as source food during the caterpillar stage. Black swallowtail caterpillars use the following as their hosts plants: fennel, dill, parsley, Queen Anne’s lace or carrot tops. They will eat the leaves and flowers of the host plant. These caterpillars will eat as much as they can to fuel for overwintering. They will not build a nest in the plant.
5 Stages of the Black Swallowtail Caterpillar
A black swallowtail caterpillar will undergo five stages of various colors while maintaining its characteristic as a caterpillar. These five stages occur from after the laying of egg to the pupa. Each of these stages is called an instar. As the black swallowtail caterpillar molts, it progresses to the next instar or stage. When this caterpillar molts or transforms, its coloring dramatically changes. In the first instar the black swallowtail caterpillar is solid black with a white band. As a full grown caterpillar, it molts into striped bands of green, white, yellow and black. An adult caterpillar can be up to 2 inches long.
Overwintering in Chrysalis
Black swallowtail caterpillars will transform into a pupa inside a chrysalis to overwinter. Once this full grown black swallowtail caterpillar stops eating, it will wander a short distance from the host plant. It will then shed its skin and transform into a pupa. The overwintering pupa will then remain in their chrysalis during the winter. It will then emerge as a butterfly in the following spring. The overwintering black swallowtail chrysalis will always be a brown color to blend with fall and winter surroundings.
Fall Black Swallowtail Caterpillars in My Garden
Last week (October 8th), I noticed the fennel in my backyard butterfly garden had 12 caterpillars feeding on it. I went inside my house and grabbed my camera. Of course, I have tried to document all the activity of the caterpillars and butterflies in my new backyard butterfly garden. I was surprised to see such a large amount of black swallowtail caterpillars so late in the year.
As a conservation photographer and storyteller, I always spend a great deal of time researching my subjects. So, after photographing these fall black swallowtail caterpillars in my butterfly garden, I started my research on overwintering caterpillars.
I thought the info was enlightening and wanted to share some of this knowledge.
At this posting the caterpillars are no longer on the fennel. I have searched my backyard for chrysalis. So far, I have not found any but will continue looking.
Thank you for reading my Field Notes blog, and I hope you will share this post with others.
Let’s protect our wildlife and nature!
All the very best,
Lori
- Celebrate Earth Day 2024April 22 is Earth Day 2024. Thus day us a reminder to take time to make our commitment to help protect and take care of our planet.
- Article Published in Nature Vision MagazineMy article “Power of Seascapes” published in the Spring 2024 issue of Nature Vision Magazine, which is a publication of Nature Photographers Network.
- American Wigeon: Profile of the Gregarious DuckAmerican wigeon profile and in the field notes about a gregarious, migrating duck along the Atlantic coast of the United States.
- Monarch Butterfly Life Cycle Page Added to My WebsiteMonarch butterfly life cycle page with diagram, information and images of the monarch life cycle can be found at Lori A Cash Conservation Photography, LLC website under the Butterfly Habitat Oasis Project page.
- Virginia’s Habitat Connectivity Hub LaunchedIn January 2024 Virginia’s Habitat Connectivity Hub was launched by Wild Virginia along side the Virginia Safe Wildlife Corridors Collaborative.
American Bullfrog American Bullfrog Sitting on Pine Needles backyard butterfly garden behind the scenes bird photography birds birds of prey black swallowtail caterpillars bullfrogs butterflies butterfly conservation Butterfly conservation photography calendars caterpillars conservation flowers Fort Monroe National Monument Frogs insects in the field Lori A Cash milkweed monarch butterflies monarch butterfly monarch conservation NANPA nature nature photography Nature Photography Day Norfolk Botanical Garden osprey photo exhibit photography photography tips pollinators publication published red foxes red fox kit seascapes songbirds sunrise sunrises sunsets tips Virginia Virginia conservation Virginia Conservation Network Virginia wildlife Virginia wildlife conservation wildlife wildlife conservation Wildlife Corridors wildlife photography Zazzle
Love the post and the update on your butterfly garden. Always great information and images!!!!
Thank you so much, Katy!
Great video, too, showing the many caterpillars!
Thank you, Katy!
I’m watching 2 on my carrot tops right now. Saw one as a tiny black with white. Wasn’t to catch them going to transform. Sneaky buggers. Lol