These fecal particles are found in the highest concentrations in pillows, mattresses, carpeting, and upholstered furniture. They float into the air when anyone vacuums, walks on a carpet or disturbs bedding, but settle out of the air once the disturbance is over. Dust mite-allergic people who inhale these particles frequently experience allergy symptoms. There may be many as 19,000 dust mites in one gram of dust, but usually between 100 to 500 mites live in each gram. Each mite produces about 10-20 waste particles per day and lives for 30 days.
Mites eat particles of skin and dander, so they thrive in places where there are people.
Dust mites don't bite, cannot spread diseases and usually do not live on people. They are harmful only to people who become allergic to them. While usual household insecticides have no effect on dust mites, there are ways to reduce exposure to dust mites in the home. Molds are commonly found in outdoor air. However, any house can develop a mold problem given the right conditions.