Dust mites are tiny spiderlike creatures (arachnids) that feed mostly on flakes of dead human skin. Mites do not bite humans or spread disease.
Dust mites are usually found where conditions indoors are warm and damp (high humidity). Dust mites are found mostly in carpeting, bedding, pillows, mattresses and box springs, furniture, and stuffed animals. Having dust mites in the home is not caused by poor house cleaning.
The number of dust mites tends to decrease during the winter months and at high altitudes.
WebMD Medical Reference from Healthwise