Computer reconstructions of Archimylacris eggintoni, a Carboniferous stem-group dictyopteran ('roachoid'), are presented. A siderite-hosted specimen was scanned using high-resolution X-ray microtomography (µCT), and a 'virtual fossil' was created with a resolution of 17.7 µm. This has revealed the morphology in great detail, including adhesive limb structures indicative of climbing and specializations for rapid movement. The antennae are filiform, and the mandibles are comparable to those of certain extant cockroaches, suggesting a similar generalist, saprophagous diet. The reconstruction reveals a high degree of specialization, and provides insights into the mode of life of these common Palaeozoic insects. Further µCT study of insect fossils has the potential to supplement wing venation with new characters, and hence improve fossil insect phylogenies.