Dust mites belong to the family of eight-legged creatures called arachnids.
This family also includes spiders, chiggers and ticks. Dust mites, which can only be seen with a microscope, are hardy creatures that multiply easily in warm, humid places. They prefer temperatures at or above 70 degrees, with relative humidity at 75-80 percent. Mites die when the humidity falls below 40-50 percent and are rarely found in very dry climates. Although dust mite populations decrease during winter in areas where the climate is cold and dry, some sensitive people report that their symptoms worsen at that time.