When fully grown, the caterpillars will turn into chrysalids, and in preparation for this they will, according to the species, descend to the floor of the cage (previously scattered with soil, leaves and grasses) or spin themselves up on supports (also provided in the cage for the purpose).
Very careful watch has to be kept in order not to miss this process, for it takes place in the space of a minute or two. The chrysalis stage is a resting period, and nothing more need now be done until the butterfly is ready to emerge.
( Swallow Tail Pupation )
Swallow Tail Pupation showing