cocoon
If you happen to find the cocoon of a moth or the crysalis
of a butterfly place it in a glass jar. If the cocoon or
crysalis is attached to a twig just break the twig and put the
piece of twig with the cocoon on it into the jar. Cover the jar
with thin cloth or screen. Place a damp sponge on top of the
jar to keep the humidity within the jar high. Keep the sponge
moist at least most of the time. Lay a piece of plastic wrap
loosely over the sponge to keep it from drying so fast. Look
at the cocoon often. If you are lucky you may see the moth
emerge from the cocoon. It may take days, weeks or months for
the moth to emerge.