Dermatophagoides Pternyssinus or the European dust mite is one of the major causes of dust mite allergy in humans. These microscopic translucent mites feed on household dust which is a mixture of dead skin flakes, fabric, mould and other substances. Though dust mites don’t bite their digestive enzymes which linger in their excrement, which are tiny enough to be sucked in while breathing causes moderate to severe allergic reactions of the skin or respiratory system to some people.