At the weekend we visited the European Synchrotron Radiation Facility in Grenoble, France with Andrew Parnell and other collaborators from Physics and Chemistry. The location was more spectacular than I had imagined, in a valley with towering mountains on either side. We had 3 days of “beam time” and made full use of the time, keeping measurements running 24hrs a day for those 3 days (Emma bravely volunteered to be on the night shift). We were measuring the butterflies that we collected in Colombia and Panama in January, using small angle x-ray scattering to measure the scale structure variation. This is far out of my field of expertise so being able to work with colleagues in other disciplines is great. This should (once the data is analysed) tell us how the scale structures vary in order to produce the variation in iridescence that we see in the wild. We can then link this up to genetic differences between the butterflies (this is where our expertise comes in) to find out how structural colours can be controlled genetically and developmentally in biological systems.