Coloured scanning electron micrograph of a head louse (Pediculus humanus capitis). The head louse is a small insect, usually 1-2 mm long, with a large abdomen and legs equipped with sharp claws for gripping hair. Lacking wings, these parasites have a slightly narrower head than their body and use their piercing mouthparts to dig into the skin, draining blood. Thriving on the human scalp for over 100,000 years, they cause itching and discomfort without transmitting diseases. Magnification: x80 when printed 10 centimetres wide.