Blood filling bed bug Cimex lectularius, approximately 6 mm in size, as it feeds on its human host. Bed bugs feed by injecting a sharp mouthpart called a stylet into the skin. The bed bug磗 saliva includes an anaesthetic which numbs the pain of its bite. Bed bugs have been notorious pests throughout history and are making a comeback in many cities throughout the world. Gorged specimens can survive several months between blood meals.