Last week I used a photo of a Black Swallowtail Butterfly in a post, which prompted one of my favorite Ecosystem Gardeners, Cindy Brown Ahern, to post this comment on Facebook:
This is such a beautiful creature, and YOU can do something as simple as planting parsley, dill, fennel, carrots in your garden to provide a food source for the caterpillars in addition to flowers to provide nectar for the adult butterfly!
Carrots, Parsley, Dill, Fennel, Queen Anne’s Lace: not native
And this is a very true statement, Black Swallowtail caterpillars do, indeed, use all of these as host plants. But I started to wonder what these caterpillars ate BEFORE the European settlement when none of those plants were present in this country.
So I started to research this question. I paged through all of my butterfly gardening books, but each and every one of them said the same thing: “Black Swallowtails use members of the carrot family (Apiaceae) including parsley, fennel, dill, Queen Anne’s Lace, and carrots.”
Same story online, even at native plant society pages.
So, What IS Native?
Now I am nothing if not determined, so several hours later I FINALLY found the answer at the Lady Bird Johnson Wildflower Center. They have an amazing plants database which is searchable by plant family.
I searched on Apiaceae and discovered that there are 82 native members of this family, many of them endangered.
But, not all of them stated that they were a host plant for the Black Swallowtail. So I entered “Black Swallowtail host plant”
into the search box and ended up with three species:
- Zizia aurea (Golden Alexander)
- Polytaenia texana (Texas Prairie Parsley)
- Polytaenia nutallii (Nuttall’s Prairie Parsley)
This is a great start!
What to do now?
I am not suggesting that you stop planting parsley, dill, or carrots for the Black Swallowtails in your butterfly garden, but fennel can be a little aggressive in the garden, and Queen Anne’s Lace is invasive in many areas (but is a main ingredient in many wildflower mixes which I call “meadow in a can”), so I’d avoid both of those.
AND, if any of the above native plants are appropriate to your site, add them to your garden.
ALSO, plant some of the other 82 native Apiaceae species and watch them diligently. If you notice Black Swallowtail caterpillars on any of those plants, take a photograph and send it to the Lady Bird Johnson Wildlflower Center. It may very well be that we have lost some knowledge of host plants for this butterfly.
And please let me know here if you notice Black Swallowtails using any of these plants. It would be so exciting if we could regain the knowledge we have lost in this area.
If you can, please support the Lady Bird Johnson Wildflower Center. They do amazing work.
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More From Ecosystem Gardening
We plant parsley every year just to attract the caterpillars and black swallowtail butterfly. I can send pictures if you want.
Where do swallowtail caterpillars go to become a chrysalis? They leave my parsley. Or does a bird eat them off the parsley.?
Black Swallowtail caterpillars
I just found your site by querying "What caterpillars eat zinnia?"
I have a caterpillar on zizia aurea that I thought looked like a black swallowtail. Now I know it is one. Thank you!
To the person who does not want to lose her dill to caterpillars - plant more dill.
Could go purchase some Golden Alexander (Zizia Aurea) plants, or more dill or parsley plants (hopefully organic plants non neonicotinoid) and put them in your garden or in a pot outside and pick the leaf your caterpillars are on and put the leave on the new plants.
Or you can buy your dill for this year at a farmer's market and plant much more next year!
I just witnessed one of the caterpillars on my dill plant shedding it's skin!!
But i honestly don't know what to do with them
I have two of them
When i was looking at my dill plant, i saw a eastern black swallowtail caterpillar and moved it on my parsley. The next day, the whole parsley was gone and i couldn't find the caterpillar anywhere but when i looked at my dill plant, there were two more caterpillars...and now I don't now what to do with them because I don't want them eating my dill.
Saw a black swallowtail cat
I found a black swallowtail caterpillar today on some Queen Anne's Lace that I allowed to grow in my flowerbed. I also have dill (because I love the scent) and wild carrots in the same 20ftx35ft bed. I am researching a bit on the subject so I can educate my grandkids since they were with me when I found it. They watched it for about half an hour and were amazed! Sorry I did not get a pic. We are in Middle TN.
Zizia aurea host plant
I put Zizia aurea in about 5 years ago, last year was the first year I found black swallowtail larvae on them, but not until late in the summer, I think it was September. Hoping for more this year, last year was a tough year for butterflies all around it seemed.