Mites, along with ticks, belong to the subclass Acarina (also known as Acari) and the class Arachnida. They have exploited an incredible array of habitats, and because of their small size (most are microscopic) most go totally unnoticed. There are over 45,000 described species of mites[1]. Scientists believe that we have only found 5% of the total diversity of mites. Mites are believed to have existed for around 400 million years. Mites cause several forms of allergic diseases, including hay fever, asthma and eczema. Perhaps the best-known mite is the house dust mite. When these mites are inhaled or touched to the skin, the body generates the antibodies which effects the discharge of chemicals known as histamines that results in swelling and irritations to the upper respiratory passages especially developing the asthma and hay fever like symptoms.

When you are likely to be exposed to substances that give you a reaction, eg when you are house cleaning, you should wear a mask. It is the fecal pellet, sometimes called frass, of the mite that causes dust mite allergy. This fecal pellet is a round pellet about 20 microns wide, and it contains proteins which cause our allergic reactions. A level of 100 mites per gram of dust is considered risky for allergy and asthma susceptible people.