Diatomaceous earth is a very fine white powder, used for insect control among other things. According to my research on the webernets, it works by "cutting up" the exoskeletons of insects, and drying them out resulting in death. Because this substance works through mechanical means rather than chemical, it is completely harmless to humans, pets (except your Madagascar cockroach), and is even found in many foods that we eat. However, no amount of searching I do can find me an answer to the simple question: why doesn't it cut humans? The only answer that I get is that it is "too small." Huh? If I have a sharp knife, and I make it even smaller, it's only become sharper, thus more capable of cutting me. How is this substance able to cut insects but not humans?