As is applicable to other whites, orangetips, sulfurs, and swallowtails, a cabbage white larva will form a cremaster and girdle before forming a chrysalis.  The cremaster is the silking of the butt end of the larva to the surface; whereas the gridle is the silk strands fastened around the ventral side of the chrysalis to secure it to the place where it pupates (in this case, the host plant pink cabbage).