Mites, along with ticks, are small arthropods that belong to the subclass of Acarina. They are among the most diverse and successful of all of the invertebrate groups. They have managed to exploit an incredible array of habitats and because they are so small (the majority being microscopic), they often go unnoticed. It is estimated that there a total of 48,200 different species of mites that have been described up to this date. Many mites live freely in soil or water, but there are also a large number of species that live as parasites on plants, animals, and some that feed on mold.
Mites, in general, are harmless to humans. However, there are a few species of mites that can colonize humans directly, acting as vectors for disease transmission, or cause or contribute to allergenic diseases. Mites that colonize the human skin are the cause of several different types of itchy skin rashes, such as grain itch, grocer's itch, and scabies. Chiggers are known for for their itchy bites, but they can also spread diseases in some limited circumstances, such as scrub typhusDust mite are known to cause several different forms of allergenic diseases, such as hay fever, asthma, and eczema, and are also known to aggravate atopic dermatitis.