Bedbug head. Coloured scanning electron micrograph (SEM) of the head of a bedbug (Cimex sp.). Antennae are seen at top right, with compound eyes (orange) at the sides of its head. Its stylet (centre), a piercing mouthpiece, is used to suck blood from warm-blood animals, including humans. Bedbugs are generally only active at night, hiding in crevices in walls and furniture and in bedding during the day. Although they do not transmit disease, their saliva can cause itchy swellings on the skin. Magnification: x40 when printed 10 centimetres wide.