Demodicosis lesions on a male patients face. Demodicosis is caused by an infestation of Demodex sp. mites. These mites, which are found on almost everyone, live in hair follicles on the face. Normal levels of mites are symptomless, but certain skin conditions or a compromised immune system can lead to the mites multiplying out of control leading to scaly, itchy, red skin. Treatment is with topical anti-parasitic drugs.