Last year I surprised Dan with a science project. I am not the scientist in the family so this does not happen often. He was really blown away, and wanted to repeat it this year. It is the caterpillar-to-butterfly metamorphosis. Barbara found the caterpillar in her garden, happily munching on a dill plant, and she was very willing to donate it.
We put it in a quart jar with some dill and parsley, covered the opening with waxpaper and a rubber band and poked holes for air. The jar then stood on the kitchen counter in a low-light area.
It only took a day or two for the caterpillar to cocoon. The day before yesterday the cocoon started to turn black, and as we found out this morning, it took only 10 days from caterpillar to butterfly. I think it is a female black swallowtail (Papilio polyxenes).