This is one of my very favorite projects to do with my kids–I might get more excited about it than they do. We have Swallowtail butterflies where I live, so I plant lots of parsley for them in the garden. (Swallowtails eat plants from the carrot family: Queen Anne’s lace, carrots, dill and parsley).
I got so into watching butterflies hatch, my husband and boys bought me this field guide one year for mother’s day, and I love it. I never thought a book about fancy worms would make my day–yet another surprise of motherhood.
I pick the parsley stem the caterpillar’s on, and put the whole thing in a jar. Then I fill the jar with lots of parsley. I use a canning ring for the lid, and mesh fabric or cheese cloth works well for the top. I like to reuse mesh bags fruit comes in–if the mesh is large and the caterpillar is super tiny, consider doubling up the mesh so the caterpillar can’t escape. (If you look carefully at the photo below, you can see the caterpillar at the very bottom of the jar).
I used to put a few drips of water in the jar, but the caterpillars seem to get everything they need from the parsley. Make sure you keep fresh greens in the jar for them–they eat A LOT. They grow so much, you can see quite a bit of growth in just one day.
If there’s a way to tell caterpillar gender, I don’t know what it is–but the male and female butterflies have very different coloring, so when the butterflies hatch, it’s obvious whether they’re male or female. This very small caterpillar lived in the jar for 6 days before starting her cocoon. If you find larger caterpillars, closer to their time of building a cocoon, you’ll have fewer days to watch them being caterpillars.
It’s hard to tell in the picture, but she found a place on the side of the jar, and connected herself to it with tiny white threads. I kept a close eye on her, wanting to photograph the change between caterpillar and full cocoon, but it happened very quickly.
A watched pot never boils, and a watched cocoon never hatches–I haven’t been able to watch a butterfly in the process of hatching, but their wings are wet and floppy when they first emerge–let the butterfly hang out in the jar until the wings dry and look normal. Here are what wet wings look like:
I happened to run across my childhood copy of “A Girl of the Limberlost” during all of this butterfly observing, and began rereading it–although parts of it are dark, it’s a nice companion to this science-y project.