Demodex skin mites live on sebum (facial oil). Most adults have one or two per square centimeter of facial skin. They live in your facial pores and hair follicles around your eyebrows and eye lashes. They crawl around your face at night to mate then return to your pores to lay their eggs and die. They have no anus so release all their faeces at once in your pores after death.
Source:
Rosacea may be caused by mite faeces in your pores