Human demodex has no intermediate host. It passes its whole life in the hair follicle and sebaceous glands of man. It is bisexual and reproduces through intercourse at the openings of hair follicles, after which it goes back to surrounding hair follicles and sebaceous glands to lay eggs and reproduce.

The life cycle of human demodex can be divided into five stagers. It is estimated that about 12 hours after mating, the demodex will lay its eggs which will hatch 60 hours later. After 36 hours of feeding, the demodex larva will moult into undeveloped protonymphs which move with sebum. After another 72 hours, they will moult again into nymphs which are stronger. They are now capable of climbing out of hair follicles and sebaceous glands to the surface of the skin. Another 60 hours later, they finally moult into adult demodex. It takes about 14 days to complete a whole life cycle. The lifespan of a female demodex is longer, about 30-60 days that of a male is shorter. Human demodex is slow in motion, but will increase in temperature. It avoids light, and loves warmth. Therefore, it is more active when its human host is sleeping. Most adult demodex crawl out of the hair follicle at this time to find mates to copulate at the openings.

During these five stages of development , the demodex will molt its shell once and molt its skin thrice. It pierces with its pincers into its human host's histolytic to feed, absorb nutrients from the hair follicles and sebaceous glands and complete its life cycle. Its secretion, excretion and dead bodies will accumulate in the hair follicles and sebaceous glands. Its parasitic activities will cause physio-chemical stimulation and local adverse reaction. This may be the basis of the human body? How does it affect our health? Attention and further study are needed to clarify these questions.

There are two styles of the chelicerae inside the pleural aperture. The styles stick from the basal bone and turn to the rear first, then turn down and extend to the pleural aperture leaning against the plain-tube wall. The two club-shaped on chin styles finally protrude from the rear edge of the pleural aperture to form an incomplete partition between the styles. The stylets are capable of penetrating the host's histocytes. They then suck the cell sap (cytochylema) through the laryngeal bulb into the body.

If the demodex are to numerous, they will widely damage the tissues and cause histo-pathalogical response, and lead to diseases, but they are likely to sap the skin tissue nutrients of their host and enlarge the pores, thereby roughening the skin and affecting the beauty of the host.

A new treatment available is seabuckthorn oil (Hippophae rhamnoides), which is the active ingredient in Facedoctor soap. Its activity is targeted against the mite to reduce the inflammation under the skin and therefore provide relief of the mechanisms that cause the rosacea complex of symptoms. The advantage that patients find with the soap is the elegance of the cleansing vehicle in otherwise sensitive skin, the presence of Vitamin E and aloe Vera which provide additional healing properties, and other active ingredients such as astragalus membraceus and spirodela polyrhiza, useful yeasts that augment the activity of the seabuckthorn oil.

My patients have found this to be well tolerated and useful either as monotherapy or in addition to their other topical and/or systemic medications. We conducted a small placebo-controlled double-blind study in the office which showed that the majority of patients had a reduction of symptomatic erythema as well as reduction of response to triggers.