Parsley Caterpillar to Chrysalis

Black Swallowtail Butterfly

Black Swallowtail Butterfly

I’ve been noticing a lot of parsley caterpillars on my young carrot plants. As these are the larval stage of the black swallowtail butterfly and there are lots of these butterflies in the garden, I wasn’t surprised to see them.  I decided to take one and experiment to see if I could watch the process of metamorphosis.

In looking online I’d found that the 2″ green and black caterpillars were the final instar of the caterpillar’s growth. Earlier instars are small and often look like bird dropping – a great method of camouflage!

Parsley Caterpillar

Parsley Caterpillar

This final stage before metamorphosis has a little trick up its sleeve to protect it if it comes under attack. If the caterpillar is disturbed or threatened, a little yellow “forked tongue” called an osmeterium shoots out of the caterpillar’s head and can startle a bird or other threatening animal. In addition, it’s said to release a scent that can deter predators. It only took a couple touches to the caterpillar to cause it to use its osmeterium against me!




But back to my experiment…

I put the parsley caterpillar in a large jar with a number of parsley and carrot leaves. It spent the first day eating but the next day was very different. The caterpillar stayed on a branch of the parsley and didn’t move. It was bowed out slightly from the branch, attached by the two ends of the caterpillar. I wasn’t sure if it had died or if it was getting ready to form a chrysalis (cocoon).



The very next morning my question was answered. The bright green caterpillar was gone and in its place was a brown chrysalis. I’m amazed how quickly this all happened. Overnight the transformation occured.


Chrysalis in a Jar

Chrysalis in a Jar

I’ve trimmed off the leaves of the parsley stem that the chrysalis is on and placed it back in the jar. I’ll be looking for any changes along the way and hoping to see the emergence of a black swallowtail butterfly.


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