Bumblebees are important pollinators, that are declining rapidly in number and need urgent protection. Visual cues are extremely important for bumblebee activities and survival so a full understanding of the micro-and nano-structure of their eyes will help us to better understand their vision and how it is affected by rapid habitat changes. Here, we present the first report on imaging of 3D structures with sub-100 nm resolution of an unstained bumblebee compound eye using X-ray holographic tomography. This study demonstrates the potential of using X-ray nano-tomography for bulk samples for zoological studies on insects. Compared to the other commonly used methods, such as TEM and FIB-SEM, X-ray nanoCT is non-destructive and relatively fast, and has the potential for providing a better understanding of a broad range of biological materials. [ABSTRACT FROM AUTHOR]