In fact, humans are the only habitat for Demodex folliculorum. They are born on us, they feed on us, they mate on us, and they die on us.

Their entire life cycle revolves around munching your dead skin cells before kicking the teeny tiny bucket.

So reliant is D. folliculorum on humans for their survival, research suggests, that the microscopic mites are in the process of evolving from an ectoparasite into an internal symbiont – and one that shares a mutually beneficial relationship with its hosts (that’s us).

In other words, these mites are gradually merging with our bodies so that they now live permanently within us.

Source paper:

Human Follicular Mites: Ectoparasites Becoming Symbionts

https://academic.oup.com/mbe/article/39/6/msac125/6604544?login=false