Your eyebrows are home to tiny mites, bacteria, and fungi that live on or near almost every human face. The most well-known residents are microscopic mites that burrow into hair follicles, feed on skin cells and oil, and emerge at night to mate on the surface of your skin. Most people carry them without ever knowing it.
The Mites Living in Your Follicles
Two species of mite call your eyebrows home. The first, commonly known as the follicle mite, prefers smaller hair follicles like those in your eyebrows and eyelashes. It feeds on dead skin cells. The second species lives deeper, settling near the oil glands inside those follicles, where it feeds on sebum, the greasy substance your skin produces to stay moisturized.
These mites are extraordinarily small, measuring between 0.15 and 0.4 millimeters long. Several of them could fit on the head of a pin. Under a microscope, they look slightly transparent, covered in tiny scales, with an elongated body split into two segments. The front segment has eight stubby legs and a mouth built for consuming skin oil and cells. They look, frankly, like something from a science fiction film, but they’re one of the most common animals on Earth.
What They Do at Night
During the day, these mites stay buried headfirst inside your hair follicles. Once it gets dark, they crawl out onto the surface of your skin to find a mate. They move painstakingly slowly, searching for another mite, mating, and then retreating back into the safety of a follicle before daylight. This entire cycle of feeding, mating, laying eggs, and dying plays out in about 14 to 21 days. Females deposit eggs inside the follicle, larvae hatch and feed, then develop through two stages before reaching adulthood and starting the process over again.
How Common They Are
Nearly everyone carries these mites by adulthood. Prevalence increases with age because oil production and the cumulative years of exposure give mite populations more time to establish. Among adults over 60, roughly 59% test positive when researchers look for them under a microscope. Younger adults carry them too, often without any detectable symptoms. You likely picked yours up through close contact with family members during childhood, or through shared pillows and towels.
Bacteria and Fungi on Your Brows
Mites aren’t the only residents. Your eyebrow skin, like the rest of your face, hosts a community of bacteria and fungi that make up its normal microbiome. One of the most notable fungi is a yeast called Malassezia, which lives naturally on skin across your face, scalp, and hairline. In small numbers, Malassezia is harmless. It feeds on the same skin oils that attract mites. But when it overgrows and gets into hair follicles, it can cause a condition called fungal folliculitis, which looks like small, itchy bumps, often on the forehead and near the hairline.
Bacteria are present too. The skin around your eyebrows is colonized by the same mix of microbes found elsewhere on the face, including species that help regulate skin health by outcompeting harmful organisms. This bacterial layer is part of your skin’s defense system. Problems only arise when the balance tips, whether from excessive oil production, immune suppression, or antibiotic use that wipes out protective species.
When These Residents Cause Problems
For most people, the mites, bacteria, and fungi in your eyebrows coexist peacefully with your skin. You’ll never feel them or notice any effect. Problems start when populations grow beyond normal levels. For mites specifically, researchers define overgrowth as a density greater than five mites per square centimeter of facial skin, or eight or more mites found on the eyelashes of a single eye.
When mite numbers spike, symptoms can include itching, redness, flaky skin at the base of your eyelashes or eyebrows, and a gritty or burning sensation in the eyes. This is linked to conditions like blepharitis (inflammation of the eyelids) and can overlap with rosacea. People with weakened immune systems or conditions that increase facial oil production are more prone to overgrowth.
For Malassezia, overgrowth tends to happen in warm, humid conditions or when oil production increases. The resulting fungal folliculitis is often mistaken for acne because the bumps look similar, but it doesn’t respond to typical acne treatments.
Managing Overgrowth
If mite populations get out of control, tea tree oil is the most studied treatment. Concentrations ranging from 5% to 50% have been tested, though lower concentrations are generally preferred around the eyes to avoid irritation. A Cochrane review found that the evidence for tea tree oil’s effectiveness remains uncertain for short-term treatment, but it is the most commonly recommended option in clinical practice. Treatments typically involve applying diluted tea tree oil to the lash line and brow area daily over several weeks.
Keeping your face clean helps maintain balance across all these organisms. Washing your eyebrows and eyelids with gentle cleansers removes excess oil that feeds both mites and yeast. For fungal overgrowth, antifungal cleansers or topical treatments can bring Malassezia back to normal levels. The goal is never to eliminate these organisms entirely. Your skin’s ecosystem depends on them being present in the right proportions.