The parasite eats, sleeps, mates and dies on the face of humans

James Weiss, a microscopist at Bournemouth University, UK, filmed Demodex beetles, a parasite that feeds on sleeping and mating on people's faces. Specifically, Mr. Weiss shaved a small black spot on his forehead with a glass slide, then placed it under a microscope and filmed it.

Demodex, a parasite less than a millimeter in length, belongs to the family of mites, and is the smallest of the arthropods. They are fearsome and harmless. This species often crawls out of hiding at night to eat dead skin cells on people's faces. After eating, they will enter the hair follicles and sebaceous glands to lay eggs. This parasite is very difficult to detect.

In Weiss' footage, the end of Demodex's body has spherical droplets, which are the sebum they have digested from human skin. Inside the hair follicle is where the male and female beetles pair. Thanks to the use of melatonin secreted by the human skin at dusk, they are able to mate all night. The eggs of this parasite will hatch after 3, 4 days, and mature after 7 days. However, their lifespan is quite short, usually lasting only about two weeks.

Demodex is about 0.3 mm long, so it cannot be seen with the naked eye. This parasite tends to spread through close contact between family members.

It is estimated that about 23-100% of healthy adults have the parasite Demodex. Only when we have skin problems do we know about their existence. Recent research shows that Demodex is not the culprit that causes many skin inflammations.

Isabella Humphrey

Update 27 June 2023