If you look closely, you will notice when their old head covering is about to come off, and should be able to find this covering. The 4th and 5th instars that you collect will likely pupate within a week. This process is fun to watch, but it happens quickly. Be careful to not jostle the container while the larvae are pupating. The pupa stage lasts nine to 14 days.
Pupae turn darker the day before butterflies emerge, and look black on the day they emerge.
At this point, the wings are visible. The butterflies usually emerge in the morning, and watching this happen is also fun, but hard to catch. Their wings will be soft, flexible, and wet when they emerge. If they fall, carefully pick them up by holding the thorax, and hold their legs next to the top or side of the cage. They need to hang with their wings pointed down.