Researchers have known for more than a century about the Demodex mites on human skin. The creatures have also been investigated as a potential cause of the skin disorder rosacea.
However, it was believed that just a small minority of people played host to the translucent critters.
Megan Thoemmes, a graduate student at North Carolina State University, scraped the sides of people's noses at citizen science events in Raleigh, North Carolina.
Thoemmes and colleagues tested hundreds of people and found mites 14 per cent of the time, 'NPR' reported.
The number seemed suspiciously low so the scientists looked for mite DNA on human faces rather than the mites themselves.
In DNA tests of 29 people, 100 per cent of those over age 18 carried DNA from Demodex mites.
Tests on more people have also come up with the same 100 per cent number, Thoemmes said.
"Realising that everyone has them and they're likely not causing any problems, it's pretty reassuring," Thoemmes said.
Scientists don't know how the mites spread among humans; one theory is that they're passed on from mother to child while breast-feeding.
The study was published in the journal PLOS ONE.