Mites (Acariformes) are small arthropods (like the tick and spider) that usually have eight legs. They are generally smaller than 0.1 to 1.0 mm and with the naked eye hardly or not perceptible. There are more than 45,000 species.
Mites eat include dead animals, plants or rotting materials. Predatory mites often live of others and are in the greenhouse horticulture used as a pest control.

Some known mites
The itch mite (Acarus scabiei) is less than 0.5 mm in size and digs tunnels in the skin as the larvae also do. The itching occurs in infected individuals only after a few weeks, by an allergic reaction to the mites and their droppings.

The house dust mite (Dermatophagoides pteronyssinus) is about 0.3 mm and lives in mattresses, pillows, upholstered furniture, carpets and moldy walls. He lives i.a. of human dander. Droppings and shed skins of dust mites can cause allergic reactions such as asthma and eczema. Practical measures to reduce dust mites are removing dander (cleaning) and reducing the humidity (ventilation).

The varroa mite is an external parasite that occurs in insects, but who can only propagate in the brood of honey bees. In the adult stage they have eight legs. The adult female is cross - oval in shape, reddish brown in color, 1.1 mm long and 1.5 mm wide.