Thursday, September 2, 2010

Caterpillars: Up Close

One of the most under appreciated features of a butterfly is their larval form. In fact, most people give very little thought to these miniature eating machines. Their youth is spent gorging away on a specific host plant, shedding 5-7 "instars" before they are ready for the big sleep.

Caterpillars: up close and personal!

The smallest of caterpillars are often quite different from the final instars. This petite .5 inch cat has raise bumps and much lighter coloring than his older sibling who is approaching 2 inchs long. While most butterfly larva are host plant specific, Eastern Black Swallowtail cats are unusual in their ability to use multiple host plants. Most of the plants associated with this species are not even native plants.

Parsley, Dill, Fennel and Queen-Ann's Lace are all non-native plants frequently used as hosts by this species. It has always boggled my mind. What did these butterflies feed upon before European settlers brought these plants to the new world? One guess is
Golden Alexanders, Zizia aurea, and since it is readily available in my yard, it is one of the test components of the "Butterfly Bouquet".

With any luck this will be the end product of our experiment: Eastern Black Swallowtail. If all goes well, we should be able to watch these caterpillars go though various instar changes, until they transform into chrysalis. Will those chrysalis hatch out yet this year? I do not know, nor do I know whether EBS past the winter as eggs, larva or chrysalis. I do know they cannot winter over as adults, but I am eager to learn more. Hope you are too!

1 comment:

  1. Nice post, Cheryl. I have noticed that Black Swallowtails really go for Cowbane, Oxypolis rigidior, one of our native albeit uncommon parsleys.

    This is one of MANY species that undoubtedly had expanded tremendously since settlement and the attendant opening up of formerly forested habitats.