Dust mites. Coloured scanning electron micrograph (SEM) of two dust mites (Dermatophagoides sp.) on fabric fibres. Millions of dust mites inhabit the home, feeding on shed skin cells. They mainly live in furniture, and are invisible to the naked eye due to their size. The excrement and dead bodies of these mites may cause allergic reactions in susceptible people. Magnification: x150 at 6x7cm size.