I have 3 rue plants in a tank with cardboard on the bottom that have fed 6 + caterpillars.. a couple keep falling off... I put them back on the plants, but awhile later, back at the bottom.. I can provide more rue from the garden... When are they ready for chrysalis??
Karen says: The caterpillars eat for a couple of weeks. When they are ready to form the chrysalis they usual wander away from the host plant (Rue). Maybe that's what your caterpillars were doing.