Demodex

The forehead mite, Demodex is reported to live on the body of more than 95% of all humans. They are not easy to find, however. because they are only about 150 micrometers long - not much larger than a single-celled Paramecium. Also, they spend a portion of their lives nestled into hair follicles, where they feed on sloughing tissue and oils.

To find Demodex on your forehead (one University biology instructor we know gives extra marks for any student able to find Demodex), you need to sample your forehead and then examine the sample with a compound microscope. Holding a glass microscope slide at a 45-degree angle, carefully scrape the edge across your forehead. Collect the oily gob of discarded skin cells with a dissecting needle and place in the center of the slide. Cover with immersion oil and add a glass cover slip.

By examining dozens of these preparations microscopically over a period of a month, we hypothesized that Demodex seems to have cycles of activity that bring it out on the skin surface every few days