Unlike monarchs, painted ladies, and other brushfoot butterflies, sometimes the visible cues of swallowtail pupae (especially the tiger swallowtail ==glaucus group) can be quite subtle and difficult to visually identify.  One of the first visible cues that a glaucus-group swallowtail pupa is developing, is that the eyes can become noticeable if the pupa is held up to a light source.  See next picture.