Last week I showed you a freshly emerged adult Black Swallowtail Butterfly that spent its first hours perched on my tomato plants until its wings were pumped full of hemolymph, dry, and ready to fly.
This week I discovered a second instar Black Swallowtail caterpillar in my dill plants. All butterfly caterpillars go through 5 phases (called instars) where they eat and eat and then molt (shed their skin), growing larger through a series of 5 of these life phases.
Although most guides to butterfly gardening recommend planting dill, parsley, fennel, and Queen Anne’s Lace as host plants for Black Swallowtail caterpillars, it occurred to me that none of these plants are actually native to North America, so I did some research to find out what Black Swallowtail caterpillars ate before Europeans brought those herbs here.
I found 3 species, but there are probably many more native members of the carrot family that Black Swallowtails will eat:
- Zizia aurea (Golden Alexander)
- Polytaenia texana (Texas Prairie Parsley)
- Polytaenia nutallii (Nuttall’s Prairie Parsley)
Golden Alexanders are native to my locale in southeast Pennsylvania, so I have planted a number of these in my garden, but I hadn’t noticed any Black Swallowtail butterflies actually laying eggs on them. So this year I tried an experiment and added some pots of parsley and dill to hopefully entice the butterflies to also lay their eggs on their historical host plant.
Most butterflies are specialists, which means they must have access to just one plant (or one family of plants) on which to lay their eggs.
But the Black Swallowtail and several other butterflies are generalists, which means they can use a wider variety of plants as their larval host plants.
Unlike the Monarch Butterfly, whose caterpillars look the same throughout all 5 instars, the Black Swallowtail caterpillar goes through several changes in appearance during each instar.
During the first two instars the caterpillar has a white mark on its back which resembles bird droppings. This is a protection mechanism to keep them from being eaten by hungry birds.
I’ve been observing this caterpillar for about a week now, and soon it will molt into its 3rd instar. Hopefully I’ll be able to continue to photograph this little guy through all of its life stages.
Third instar Black Swallowtail caterpillar:
Fourth instar Black Swallowtail caterpillar:
Fifth instar Black Swallowtail caterpillar:
I have a funny story about this photo of the 5th instar Black Swallowtail caterpillars. I had spent the day birding at Bombay Hook National Wildlife Refuge near Smyrna, DE and on the way home discovered a wonderful roadside farmers market stand.
Imagine my delight as I discovered quite a few parsley starts that had large Black Swallowtail caterpillars happily munching away at the small parsley plants. So I gathered together all of the plants that were hosting these caterpillars and headed up to the cashier to make my purchase.
Non-chalantly I set them down on the counter, only to see the cashiers face go completely white. “Let me go find you some of these that don’t have worms on them,” she stuttered. “I’m so sorry about these worms.”
“It’s ok,” I responded. “I really WANT these exact plants. What you’re calling ‘worms’ are actually caterpillars for the Black Swallowtail Butterflies, and I want to take them home to watch them grow.”
Butterflies? she asked. “I’ve been tossing those things out all week long. Do you think I can watch them grow, too?”
It makes me so happy when I get to talk to people about welcoming wildlife into their gardens! I explained to the cashier how to take the plants home and plant them and then she’d be able to see the adult Black Swallowtail butterfly emerge. The cashier’s attitude went from fear and disgust to excitement as she planned to welcome these butterflies into her own garden.
After this final phase (the 5th instar) the Black Swallowtail caterpillar will create a chrysalis and then finally emerge as an adult butterfly.
I am so excited about getting to watch the whole process!
More resources for Black Swallowtail Butterflies:
More information about Black Swallowtail Butterflies:
- Black Swallowtail Caterpillar Life Stages
- Freshly Emerged Black Swallowtail Butterfly
- Raising Black Swallowtail Butterflies
- Do Black Swallowtail Butterflies Lay Their Eggs on Dill?
- What Black and White Caterpillar Eats Carrots?
- What Did Black Swallowtails Eat Before we Brought In Parsley, Dill, and Queen Anne’s Lace?
For more information about creating a butterfly garden, please see:
Carole Sevilla Brown lives in Philadelphia, PA, and she travels the country speaking about Ecosystem Gardening for Wildlife. Check out her new free online course Ecosystem Gardening Essentials, 15 free lessons delivered to your inbox every week.
© 2013, Carole Sevilla Brown. All rights reserved. This article is the property of BeautifulWildlifeGarden.com If you are reading this at another site, please report that to us