How to Grow a Zebra Swallowtail Butterfly!

It has been a full time job this summer, raising and releasing butterflies! Last summer the number of egg-laying adults and caterpillars was dismal, the lowest I’d seen in at least six or seven years. This was at least partially due to the severe weather we’d had the previous winter, which killed many overwintering eggs and caterpillars. This summer the butterflies are making up for that lost time, and breeding like their lives depend on it – which they actually do.

I’ve raised and/or released at least eighteen different butterfly or moth species from caterpillars that I've  found on the native plants in my yard this summer. Let me walk you through the process; I’ll use the gorgeous Zebra Swallowtail butterfly as my example.

Zebra Swallowtails lay their eggs on leaves of the Pawpaw tree, as the caterpillars eat only this food. So I planted Pawpaw in my yard to attract them. Along about mid-August, I saw a Zebra laying eggs on the leaves.

A week or so later I started finding the caterpillars, which had just hatched from the eggs. I started to collect them – and their leaves – and put them in screen cages for protection from birds, parasitic wasps and other predators. Here’s a photo of two 1 or 2-day-old caterpillars on their Pawpaw leaves; I placed a grain of rice on the leaf to give you a perspective on their size:

I replace the Pawpaw leaves in the cage at least once daily. Although I put the leaves in tubes of water to keep them fresh, they do dry out quickly, and the caterpillars need fresh leaves to survive and grow. Below is one of the caterpillars about 5 days after the first photo was taken, and again a few days after that. Caterpillars go through several molts before they morph into chrysalis, completely shedding their old skin to reveal the new one, and they can have very different appearances in their different stages:

When the caterpillar gets to be a couple of weeks old, give or take a few days, it starts to get restless and looks for a place to morph into its chrysalis stage. In my cages, it does this either on a dried leaf or on the side of the cage like this one:

This caterpillar is preparing to go into chrysalis; you can see the silk thread it has spun to attach itself securely to the cage. It has also "hunched" itself into a comma shape. When it is ready, it will actually shed its skin one more time, and reveal the chrysalis that has formed, below:

After another couple of weeks or so in chrysalis, the adult butterfly emerges. At first it is completely wet and looks more like a wasp than a butterfly. The butterfly below has been out of its chrysalis for ten or fifteen minutes:  

Over a period of several hours it unfolds, dries out, and pumps its wings to strengthen and prepare them for flight. 

 

Finally, the adult is ready to be released. Beautiful!

 

Last week my friends Sharon and Michael called about a caterpillar they had just found in their yard, and they emailed me a photo taken with their cell phone:

 

I knew this was some kind of moth larva. I called and asked them how big it was, and the answer was that it was bigger than Michael's index finger! After a little investigating I determined that it was an Imperial Moth caterpillar, one of the family of impressive giant silk moths that occurs here. I told my friends that I definitely wanted to raise and release this guy, so they delivered it to me the next day. Here it is, with a mug only a mother could love:

 

 

I read that this caterpillar species does not form a cocoon above ground as many moths do; instead it burrows into the ground and morphs into a pupae for the winter, encasing itself in a hard, waxy shell. So instead of putting it in a screen cage as I do with the butterflies, I put dirt and leaf litter in an old aquarium and put it in there with pine branches, one of its food sources.

 

 

This guy was almost full grown when I got it, so he ate just a little bit more then buried himself underground within a day and a half. I will keep the aquarium on my porch all winter, and hopefully he will emerge next May or June as a beautiful Imperial Moth (photo below courtesy of wikipedia.com).

 

 

Over the weekend, one of the neighborhood kids brought me another large moth caterpillar that he found in the road! This is definitely the time of year that these caterpillars come down from the trees where they have been eating, and find a place to go into their cocoon or pupae phase. You can find them anywhere, so keep your eyes open for them! (Call me at 410-7147 if you find one and need someone to raise it! Ask for Karen.) Here's the caterpillar that my neighbor brought:

 

 

I identified it as a Polyphemus Moth caterpillar, another of the giant silkworm moths. Like the Imperial Moth caterpillar, this one is as big as a large index finger. I prepared an aquarium for it, and in less than 24 hours it had wrapped itself in some Dogwood leaves I placed inside, and had already spun its winter cocoon. It should emerge in May or June, and will look like this:

 

 

I have so much more to share with you but this entry has already gotten pretty long. I'll save some for next time. And in the meantime, I will have a new challenge: my friend Nancie brought me some Mexican Jumping Beans today from Arizona, which are actually seed pods that have been inhabited by a moth larva. The larvae "jump" while inside the seed pod, reacting to heat, thus the name "Jumping bean." I'm going to figure out how to keep them over the winter and see if the moths actually emerge from the pods in the spring. Stay tuned....!