Dust mites are those tiny insects invisible to the naked eye that are found in every home.. They feed on human skin flakes and are found mostly in mattresses, pillows, carpets, upholstered furniture, bed covers and other fabric and fabric-covered items. Body parts and feces from dust mites can trigger asthma in individuals with allergic reactions to dust mites, and exposure to dust mites can cause asthma in children who have not previously exhibited asthma symptoms.