A few days ago, I went out to the garden to pick some carrots for dinner and saw the most beautiful green caterpillar with black stripes and orange dots. I didn't even have time to grab my camera right then, but later in the evening, after eating and homework and chores were done, I flipped through a field guide and found it had been an Eastern Black Swallowtail. A quick search online and I learned that, yes, they can be safely raised indoors, although its late summer appearance meant I would have to overwinter the chrysalis. I went back out to the garden to see if I could find him among the carrot tops and found a second one too.
I brought them inside and set them up in a big pretzel jar (I'm using a plastic jar instead of my usual vase since it will have to spend the winter in the garage) with lots of carrot tops and some parsley and fennel for variety (they feed off plants in the carrot family). Each evening I replace their wilted and depleted carrot tops with new ones and empty out the frass (caterpillar poop) from the bottom of the jar. (I've been trying to get the kids involved, but other than an occasional glance in the jar by one of them, it's been all me this time around).
The interesting thing about these caterpillars is that when they feel threatened, they extrude two tiny (but very, very scary) orange "horns" out of the front of their head. They also exude an odor that smells...exactly like chamomile. Which is funny, because ever since I was a child I've thought chamomile tea smells "like squished caterpillars." I have no conscious memory of squishing or otherwise encountering a swallowtail caterpillar ever before, but I must have had a run-in with one and the smell lodged deep in my reptilian brain. (I do like the smell and taste of chamomile, but it does smell like caterpillars).
This morning, they both appeared to be assuming their chrysalis-making position (clinging to the lower side of a slanted stick). When I got home this evening, they were still there, hanging out like a pair of quotation marks. I guess shedding your skin, spinning a protective coating around yourself, and getting ready to dissolve all your insides takes some preparation.
Last time I posted about raising caterpillars indoors, I received some comments expressing concern about how it might affect caterpillars, butterflies, and their environment. Everything I've read indicates that captive-reared caterpillars have a better survival rate because they're less likely to be attacked by predators (though not totally safe--we once had a very tiny praying mantis eat a very tiny monarch caterpillar we were raising). And rest assured, we raise them only to release them back into the wild, not to add to a collection.
I found our information on raising and overwintering a black swallowtail here.