Swallowtail Butterflies and Parsley?

Recently, Debbie and a few Woodbridge customers have noticed butterflies fluttering around parsley. Parsley is a host plant for Black Swallowtail butterflies to lay their small yellow eggs. When the caterpillars "hatch" they will eat the parsley or other plants in the carrot family, including dill, fennel, Queen Anne's Lace, and even carrot tops. Comparatively, Monarch butterflies will only lay eggs on milkweed.


Black Swallowtail butterflies are so easy to raise that many pre-schools and elementary schools incorporate them into their class time. At the Scituate Early Learning Center, the teachers help students locate eggs and caterpillars in the wild, raise them in an enclosure in the classroom, then release the butterflies outside.

Growing up I was taught that caterpillars make a cocoon and changed into butterflies inside. Recently, my son has taught me that caterpillars build a chrysalis.

Cocoon or Chrysalis?

The difference between a cocoon and a chrysalis is drastic (if you happen to be the inhabitant). Once the caterpillar begins its metamorphosis, it is called a pupa. Butterfly pupa attach themselves to a twig using their silk, then enclose themselves in a hard casing called a chrysalis. Within the chrysalis, their transformation completes when they hatch in the Spring.

A cocoon is the silk enclosure that some moth caterpillars spin around themselves before they finally molt into pupa from inside the cocoon. There are four stages from egg to butterfly: egg, caterpillar (eating phase), pupa (transition stage), and finally butterfly. Caterpillars grow so fast that their skin can't keep up, so five times prior to becoming butterflies, they shed heir skin (molt). The stages between molts are called "instars".

Let them eat....parsley and ...
If you are lucky enough to find Black Swallowtails in your garden at any stage of their life, you can easily help them by providing a few plants they enjoy, as well as shelter and water. Black Swallowtail butterflies drink the nectar from many flowers including purple coneflower, red clover, thistle, and milkweeds. Be sure to have a variety of these in your garden to entice them to stay around and lay more eggs. Since caterpillars are eating machines, you may want to plant more of their favorite host and nectar plants.
To learn more about the butterflies common in Rhode Island, I recommend the website: http://www.thebutterflysite.com/rhodeisland-butterflies.shtml where you can click on the butterfly's name to learn about its favorite host plants.

For more great pictures of Black Swallowtails, visit: http://www.raisingbutterflies.org/.

Research by Renee C. Brannigan