Last year, I decided to start doing some simple herb and vegetable gardening in our small back yard in NYC. One day while I was outside tending to the plants, I watched a black swallowtail butterfly flitting around, and a few days later, I saw some black worms with a white stripe in their middle eating my big dill plant. A quick check of the intarwebs told me that these were the first instar caterpillars that had hatched from the eggs my butterfly friend had laid. I watched them every day as they munched away at my dill, fascinated at how they grew and changed shape and color. I got quite attached to these little guys, and even gave them names.
One hot afternoon, after they had grown fat and juicy, and changed from their muted black and white to a brightly colored green and yellow, a wasp swooped in and stabbed poor Flash Gordon right behind his head! Horrified (and terrified of wasps), I ran into the house screaming for my boyfriend to do something. His initial reaction at my hysterics was to grab a weapon to fight off my assailant, but after realizing what was actually going on, he appeared on the back stoop with a flyswatter asking me what I wanted killed. Obviously, it was too late at that point, and poor Flash Gordon was gone.
The next day, I jury-rigged a tent over the big dill plant using whatever lumber we had in the garage and some fiberglass window screen. Then I learned another lesson: when the caterpillars are ready to enter chrysalis stage, they like to roam far away from their "host plant", and will get out of my ghetto tent pretty easily. At this point, they will get eaten by another wasp.
After another request to my beleaguered boyfriend, the heavy clay pot with my herbs and big dill plant was in our front vestibule with the last of the yellow, final instar caterpillars in tow. This one flourished, apparently living out it's chrysalis stage behind a bookcase, until the day I came out to find that velvety black swallowtail flying in my front porch.
The situation at hand was quickly fixed by opening some windows and allowing the papillon in residence access to the world. However, as it was busy transforming itself, I had been busy transforming my dill tent into a "cage" that might actually be useful.
As it turns out, my cage did last for the second wave of caterpillars to butterflies of the summer, and the final wave of caterpillars to chrysalis to my porch for the winter, then all five over-winter caterpillars hatched just this May. Hurray! But during this time, I did notice some areas that needed improvement, thus this design for a habitat that should but useful for raising caterpillars that are safe from wasps, and hatching them into beautiful black swallowtail butterflies.
Please note: the cage is just "protective custody" for the caterpillars and chrysalis, and no butterflies are held beyond a couple of hours after emerging. It takes a couple of hours for their wings to be flight worthy after they emerge, but they only have a matter of days to live. I only keep them caged until they can fly well on their own, then let them go.
Please keep in mind that I'm not a lepidopterist, and the information in this Instructable is a summary of articles I've read on the internet and my own, unscientific observations. You may want to look at the following websites for more information:
The Eastern Black Swallowtail butterfly is pretty much everywhere in the United States, and quite common in the East. As the name suggests, they are primarily black, and with wings open, just a bit smaller than my hand. They have yellow and blue spots that appear more like paintbrush strokes if you look at them closely, and an orange eye shaped mark on their lower hind wings.
Presumably, the butterflies feed on nectar in flowers, but I have not been fortunate enough to witness that. The only time I see them in the wild is when they are laying eggs. Nature has given these creatures the wonderful ability to be smart enough to know to lay their eggs on plants that the caterpillars will eat, once hatched, even though these plants are not particularly attractive to the butterflies as a place to either feed or roost. The links above will suggest that parsley is a primary food source, and even that they are called "Parsley Worms". From experience, I will say that I plant a lot of parsley and not had one caterpillar feeding on it.
Instead I find that from what I plant around my home, carrot is the favorite for egg laying, and dill is second. I've also moved caterpillars from one plant to the other, and they will switch food sources, so it seems like one plant is as good as another, it's just more about what the mother butterfly wants to lay eggs on (again, with the exception of parsley, which they don't seem to want to eat).
So, in order to get caterpillars, all you have to do is plant some dill. Just get 4" or 6" pots from your local home and garden store, throw in some potting soil and dill seeds (the planting kind, not the ones from the spice shelf). Also, a lot of grocery stores now sell live herb plants, so you may be able to get a plant ready to be eaten there.
Whichever method you use, make sure to plant way more than you think you will need. A couple of caterpillars can easily destroy a full grown dill plant. Just put the plants outside on a window ledge, fire escape, back yard, etc. and make sure to check it and water it every day. Be patient and keep checking, and one day you will see some ivory/white bubbles on your plants. Those are your butterfly eggs. Soon, you will see some tiny little black dots...don't brush them away because the next time you look they will be worm shaped with a white band around their middle - that's your black swallowtail caterpillar.
While waiting for a butterfly to come along and lay her eggs, you can be getting your habitat in order.