Original or unprocessed data is provided in support of the article “Development of structural colour in leaf beetles”. The article was accepted for publication in 2017 in the journal "Scientific Reports". Electronic supporting Information is available from the publisher. The data is structured into eight folders, each correlating to a specific data type presented in the published article. Folder 1: Photographs of the beetles at different stages of life. Folder 2: the data sets used to reconstruct the 3D volumes shown in Figure 2 (Synchrotron microtomography) in the manuscript. Folder 3: the complete set of TEM (Transmission Electron Microscopy) images available. The folder is further subdivided by beetle’s stage of life. Folder 4: optical microscope images before processing. The scale bar is included for reference. Folder 5 is relative to the Figure 5 in the manuscript: it is divided into two folders. The first one contains the Python code used to generate the simulated spectra. This file also includes the input files (i.e. the layer thickness as measured from the TEM sections). The second main folder includes the MATLAB files used to generate Fig.5 (that is, the experimental spectra collected by optical microspectroscopy and the simulated signal). In folder “Supporting”, one can find the two supporting video and the MATLAB code used to generate the supplementary images and the relative input files.