The non-invasive diagnostic methods represent a new branch of insect diagnostics, which can provide novel information especially about insects with hidden lifestyle. Computed tomography (CT) is one of the most useful non-destructive techniques allowing for both qualitative and quantitative assessments. The aim of the present study was to attain entomological information through the implementation of CT imaging, hence contributing to the spread of non-invasive imaging in entomological research. Through monitoring the development of wood-dwelling cerambycid larvae in beech branches, we point out some outputs applicable in entomological studies, which originate from CT image post-processing. We present findings on the location, and size of specimens of some hidden arthropods, as well as cavities formed by them, stemming from the maximum and minimum intensity projections, windowing, 3D-reconstruction, or virtual endoscopy, as steps of the imaging. In summary, it is expected that our findings contribute to a wider recognition of the entomological information that can be gathered from these non-invasive imaging techniques.