Miss Piggy

Yesterday morning, Miss Piggy the monarch, emerged from her chrysalis. She was very attached to me and spent most of the evening and this morning sitting on me. The baby released her first butterfly when she let Miss Piggy fly outside this afternoon. Only one more chrysalis to go - and this one is smaller than most. Could the caterpillar have quit after the 4th instar and formed the chrysalis? Email me if you have seen any research on this topic.