Caterpillars on licorice vine
...Those are American lady caterpillars.
How long until they mature and fly away? Will it perpetually go on if I leave them to develop?
The caterpillars look mature and close to pupating, so maybe a 3 weeks to a month before the butterflies will emerge from their chrysalises. There are multiple generations in Michigan, so yes, it is possible the caterpillars will appear again.