In this 25 October 2018 time lapse video, a swallowtail caterpillar becomes a pupa.
Gerrit Stronks made this video in a greenhouse in his garden in the Netherlands.
There were 10 swallowtail caterpillars in the garden. Mr Stronks put them in the greenhouse, with carrot leaves as food. All ten have become pupas by now. If all goes well, then there will be ten swallowtail butterflies flying in the spring of 2019.