What Is Scabies? Scabies is a skin infestation caused by a very tiny mite known as the Sarcoptes scabiei. These microscopic mites can live on your skin for up to two months. They reproduce on the surface of your skin and then burrow into your skin and lay eggs. This causes a very itchy, pimple-like rash to form on the skin. There are approximately 300 million cases of scabies in the world every year.