External and internal structures of eggs from two species of different order of insects (mayfly and human louse) were studied with two X-ray microtomographs. Results indicated that microtomographical techniques give similar images to what nowadays can be obtained tiwh SEM, but with the advantage of evidence of internal structures (e.g., strengthening internal chorionic structures as an adaptation to support impacts, and/or to point out blastomeric cells) permitting the study of embryo anatomy and development. With the advantage that once the volume rendering models have been obtained it is possible to study the sample in any perspective and perform as many virtual dissections as are needed to be able to understand or to better point out any structure.