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Do We Really Have Bugs Living in Our Eyebrows?

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A follicle mite as view under a scanning electron microscope.

A scanning electron microscope images of a follicle mite.

Wikimedia Commons/Alan Walker (CC SA license)
A follicle mite (shown under magnification).

A follicle mite (shown under magnification). Follicle mites are carrot-shaped, with stubby legs.

Wikimedia Commons/Blauerauerhahn (CC-by-SA license)

Question: Do We Really Have Bugs Living in Our Eyebrows?

You’ve probably picked up this little tidbit somewhere and wondered if it is true. Do we really have bugs living in our eyebrows (or eyelashes)?

Answer:

We sure do! Our skin is literally crawling with microscopic mites. Human beings host two species of mites, which are commonly called face mites or follicle mites. And they aren’t called face mites for nothing! They do prefer to live on our faces, ideally near the eyes or nose. The older you are, the more face mites you have tucked away in your facial follicles, research shows. Newborn babies are mite-free, but by age 60, virtually all humans are infested with face mites. Face mites are believed to spread from person to person via close contact. So if you’re out together dancing cheek to cheek, you may also be sharing face mites with your partner.

The Discovery of Face Mites

We’ve known about face mites since the early 1840’s, thanks to their near simultaneous discovery by two scientists. In 1841, Professor Frederick Henle was probably startled when he found the tiny parasites living in earwax, and apparently, wasn’t quite sure how to classify them within the animal kingdom. He said as much in a letter to German physician G. Simon, who in 1842 had discovered the same parasites while squeezing zits on the noses of several of his patients. Simon consulted an entomologist, and was thus able to correctly identify the critters as mites (Class Arachnida, Order Acari). Simon communicated his discovery to the Berlin Society of Naturalists.

Soon after Simon’s report of the find, it seemed everyone was getting in on the face mite frenzy. A fellow by the name of Miescher named the new parasite Macrogaster platypus, while Erasmus Wilson took to calling the mite Entozoon folliculorum. Paul Gervais paid homage to G. Simon by naming the mite Simonea folliculorum, a gesture I’m sure Dr. Simon appreciated. But in the end, a London scientist by the name of Owen had named it first, calling the mite Demodex folliculorum, and naming conventions favor the first name given a species. So, the follicle mite is still known today as Demodex folliculorum.

Over a century later in 1963, a Russian scientist named L. Kh. Akbulatova noticed that some face mites were a bit smaller than the others. He considered the shorter mites a subspecies, and referred to them as Demodex brevis. By 1972, it was determined that Demodex brevis was actually a distinct species, with unique morphology that differentiated it from the larger Demodex folliculorum. So people are colonized by two kinds of mites. Aren't we lucky?

An ophthalmologist named Tullos Coston, upon learning about follicle mites, became quite obsessed with whether the presence of mites might be responsible for disorders of the eyelids. He took to plucking a few eyelashes from each of his patients, in order to survey their face mite population, and published his conclusions in an ophthalmology journal in 1967.

What Do Face Mites Look Like?

As arachnids, face or follicle mites have 8 legs, although in the case of Demodex spp., their legs are decidedly stubby. While most mites are round or oval, face mites are long and thin, a body shape that enables them to move in and out of narrow hair follicles with ease. Face mites are tiny, measuring a mere fraction of a millimeter long. The follicle mite spends its life head-down in the follicle, gripping onto the hair or lash tightly with its feet. Strangely, face mites don’t have anuses, leading many entomologists to crack jokes about them being full of, er, feces.

What Do Face Mites Do?

Face mites spend their entire life cycle tucked away inside your hair follicles. That means everything they do – mating, laying eggs, eating – happens in your face (literally, in your face!). Occasionally, a face mite may need a change of scenery, perhaps because the follicle is getting a little crowded, or because it’s ready to find a mate. Face mites are photophobic, so they wait until the sun goes down and the lights are off before backing slowly out of their follicle and making the arduous journey (moving at a rate of about 1 cm per hour) to a new follicle. As the mite travels along in search of a new home, it probably takes a nibble or two of your skin cells. Free facial!

Follicle mites (Demodex folliculorum) typically live in groups, with a few mites sharing a follicle. The smaller face mites (Demodex brevis) seem to be loners, and generally only one will occupy a given follicle. Both species feed on the secretions of our oil glands (also known as sebaceous glands), and Demodex folliculorum is thought to feed on dead skin cells as well.

When it comes time for mating, face mites must manage the task within the confines of the follicle. The male mite’s penis is actually on his back, while the female’s genital opening is on her belly, so they can cozy up together in a tight space. After mating, the female deposits her eggs inside the hair follicle, and they hatch in about 3 days. Within the span of a week, the mite progresses through its nymphal stages and reaches adulthood.

Do Face Mites Carry Diseases or Make You Sick?

Although scientists have correlated the presence of face or follicle mites with certain skin disorders, including rosacea, no clear link has been found to suggest the parasites contribute to or cause these disorders. A healthy human adult is colonized by 1,000-2,000 follicle mites at any given time, without ill effects.

Sources:

  • Furtive Fauna: A Field Guide to the Creatures Who Live on You, by Roger M. Knutson, Viking Penguin, 1992.
  • Bugs in the System: Insects and Their Impact on Human Lives, by May R. Berenbaum, Addison-Wesley, 1995.
  • The Life That Lives on Man, by Michael Andrews, Taplinger Publishing, 1976.
  • American Medical Journal , Volume 17, 1889.
  • A Treatise on the Parasites and Parasitic Diseases of the Domesticated Animals, by Louis Georges Neumann, Baillière, Tindall and Cox, 1905
  • Scientific American: Supplement, Volume 21, Munn and Company, 1886.
  • Textbook of Medical Parasitology, by T.V. Rajan, BI Publications Pvt Ltd, 2008.
  • Diagnostic Pathology of Parasitic Infections: With Clinical Correlations, by Yezid Gutiérrez, Oxford University Press, 2000.

 

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