Insect metamorphosis is one of the most fascinating developmental processes in the natural world. Complete metamorphosis requires the breakdown and re-organization of larval tissues, and the coordinated construction and development of adult structures. The molecular events that achieve this transformation are however incompletely understood, and there is in particular a shortage of data describing changes in protein abundance that occur during the metamorphic journey. Here we provide data from a proteomic analysis of consecutive developmental stages of a laboratory butterfly as it develops from a caterpillar into an adult via pupation. This provides a dynamic reference dataset representing 2749 detected proteins. Statistical analysis identified 90 proteins changing significantly in abundance during metamorphosis, and functional interpretation highlights cuticle formation, apoptosis and autophagy during the pupal stages, and the up-regulation of respiration and energy metabolism upon emergence of the fully formed adult. A search for peptide phosphorylation modifications in the data identified three proteins with roles in muscle function suggesting developmental stage-dependent phosphorylation events.