There are two main species of dust mites which are found in 80% of homes: Dermatophagoides pteronyssinus and Dermatophagoides farinae. These dust mites are tiny and cannot be seen with the naked eye but can only be viewed using a camera with a magnification of at least 25 times. Experiments have revealed that dust mites show optimal growth in locations with a temperature of 45 degrees Celsius and 75% relative humidity. In these environments, skin flakes from humans and animals are shed more quickly and are subsequently fed on by dust mites. Thus, the more food available to them, the more the dust mites flourish and multiply.
Both the body parts and the waste droppings of dust mites are allergens for many people. Areas of the home in which greater numbers of dust mites are usually found include beds and mattresses, pillows, sofas, wardrobes, and anywhere that dust collects.

