They are so small that a dozen of them could dance on the head of a pin. They are more likely, though, to dance on your face, which they do at night when they mate, before crawling back into your follicles by day to eat. In those caves mother mites give birth to a few relatively large mite-shaped eggs. The eggs hatch, and then, like all mites, the babies go through molts in which they shed their external skeleton and emerge slightly larger. Once they’re full size, their entire adult life lasts only a few weeks. Death comes at the precise moment when the mites, lacking an anus, fill up with feces, die, and decompose on your head.I'll leave out any photographs so as not to creep out sensitive readers; you can view a gallery at National Geographic.
You learn something every day.